diff --git a/.github/workflows/run-tests.yml b/.github/workflows/run-tests.yml
index 646bf37..7a475d2 100644
--- a/.github/workflows/run-tests.yml
+++ b/.github/workflows/run-tests.yml
@@ -12,8 +12,8 @@ jobs:
       fail-fast: true
       matrix:
         os: [ubuntu-latest]
-        arangodb: ["3.10", 3.11, 3.12]
-        php: [8.2, 8.3]
+        arangodb: [3.11, 3.12]
+        php: [8.2, 8.3, 8.4]
         stability: [prefer-stable]
 
     name: P${{ matrix.php }} - A${{ matrix.arangodb }} - ${{ matrix.stability }}
diff --git a/phpunit.xml b/phpunit.xml
index e12801e..9a7472c 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,21 +1,16 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:noNamespaceSchemaLocation="./vendor/phpunit/phpunit/phpunit.xsd"
-         bootstrap="vendor/autoload.php"
-         colors="true"
-         stopOnFailure="false"
->
-    <testsuites>
-        <testsuite name="all">
-            <directory suffix="Test.php">tests</directory>
-        </testsuite>
-    </testsuites>
-    <coverage processUncoveredFiles="true">
-        <include>
-            <directory suffix=".php">tests</directory>
-        </include>
-    </coverage>
-    <php>
-        <env name="ARANGODB_VERSION" value="3.12"/>
-    </php>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.5/phpunit.xsd" bootstrap="vendor/autoload.php" colors="true" stopOnFailure="false" cacheDirectory=".phpunit.cache">
+  <testsuites>
+    <testsuite name="all">
+      <directory suffix="Test.php">tests</directory>
+    </testsuite>
+  </testsuites>
+  <php>
+    <env name="ARANGODB_VERSION" value="3.12"/>
+  </php>
+  <source>
+    <include>
+      <directory suffix=".php">tests</directory>
+    </include>
+  </source>
 </phpunit>
diff --git a/src/ArangoClient.php b/src/ArangoClient.php
index 9f69e35..e5d42e7 100644
--- a/src/ArangoClient.php
+++ b/src/ArangoClient.php
@@ -42,7 +42,7 @@ class ArangoClient
      *
      * @throws UnknownProperties
      */
-    public function __construct(array $config = [], GuzzleClient $httpClient = null)
+    public function __construct(array $config = [], ?GuzzleClient $httpClient = null)
     {
         $config['endpoint'] = $this->generateEndpoint($config);
         $this->config = new HttpClientConfig($config);
@@ -196,7 +196,7 @@ public function prepare(
     /**
      * @return mixed
      */
-    public function getConfig(string $value = null): mixed
+    public function getConfig(?string $value = null): mixed
     {
         if ($value) {
             return $this->config->$value;
diff --git a/src/Prometheus/Metric.php b/src/Prometheus/Metric.php
index 72a8173..dd170fb 100644
--- a/src/Prometheus/Metric.php
+++ b/src/Prometheus/Metric.php
@@ -25,5 +25,6 @@ public function __construct(
         public int|float|null $value = null,
         public ?array $buckets = [],
         public ?array $labels = [],
+        public null|int $timestamp = null,
     ) {}
 }
diff --git a/src/Transactions/SupportsTransactions.php b/src/Transactions/SupportsTransactions.php
index 127be4b..2d852e3 100644
--- a/src/Transactions/SupportsTransactions.php
+++ b/src/Transactions/SupportsTransactions.php
@@ -53,7 +53,7 @@ public function beginTransaction(array $collections = [], array $options = []):
      *
      * @throws ArangoException
      */
-    public function abort(string $id = null): bool
+    public function abort(?string $id = null): bool
     {
         return $this->transactions()->abort($id);
     }
@@ -64,7 +64,7 @@ public function abort(string $id = null): bool
      *
      * @throws ArangoException
      */
-    public function rollBack(string $id = null): bool
+    public function rollBack(?string $id = null): bool
     {
         return $this->transactions()->abort($id);
     }
@@ -75,7 +75,7 @@ public function rollBack(string $id = null): bool
      *
      * @throws ArangoException
      */
-    public function commit(string $id = null): bool
+    public function commit(?string $id = null): bool
     {
         return $this->transactions()->commit($id);
     }
@@ -89,8 +89,8 @@ public function transactionAwareRequest(
         string $method,
         string $uri,
         array|HttpRequestOptions $options = [],
-        string $database = null,
-        int $transactionId = null,
+        ?string $database = null,
+        ?int $transactionId = null,
     ): stdClass {
         if (is_array($options)) {
             $options = $this->prepareRequestOptions($options);
diff --git a/src/Transactions/TransactionManager.php b/src/Transactions/TransactionManager.php
index 97aa04f..872e0c8 100644
--- a/src/Transactions/TransactionManager.php
+++ b/src/Transactions/TransactionManager.php
@@ -37,7 +37,7 @@ public function getTransactions(): array
     /**
      * @throws ArangoException
      */
-    public function getTransaction(string $id = null): string
+    public function getTransaction(?string $id = null): string
     {
         $this->validateId($id);
 
@@ -72,7 +72,7 @@ public function begin(array $collections = [], array $options = []): string
     /**
      * @throws ArangoException
      */
-    public function commit(string $id = null): bool
+    public function commit(?string $id = null): bool
     {
         $id = $this->getTransaction($id);
 
@@ -87,7 +87,7 @@ public function commit(string $id = null): bool
     /**
      * @throws ArangoException
      */
-    public function abort(string $id = null): bool
+    public function abort(?string $id = null): bool
     {
         $id = $this->getTransaction($id);
 
@@ -102,7 +102,7 @@ public function abort(string $id = null): bool
     /**
      * @throws ArangoException
      */
-    protected function validateId(string $id = null): bool
+    protected function validateId(?string $id = null): bool
     {
         if (
             empty($this->transactions)