* 5.4:
  Fix LICENSE CI check
  fixes retrieving multiple values for extra fields
  [String] Remove duplicates in fold maps
  fail with a meaningful error when a needed package is missing
  [DependencyInjection] Fix combinatory explosion when autowiring union and intersection types
  Update license years (last time)
  [Tests] New iteration of removing `$this` occurrences in future static data providers

* 5.4:
  [Serializer] Fix CsvEncoder decode on empty data
  [Tests] Migrate data providers to static ones
  stop using assertObjectHasAttribute()/assertObjectHasNotAttribute()
  [Dotenv] Fix phpdoc Dotenv
  [Config] Fix phpdoc nullable
  Fix some typos

… `/Tests/` (OskarStark)

This PR was merged into the 6.3 branch.

Discussion
----------

[PHPUnit 10] Use `TestCase` suffix for abstract tests in `/Tests/`

| Q             | A
| ------------- | ---
| Branch?       | 6.3
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | Refs symfony/symfony#49233
| License       | MIT
| Doc PR        | n/a

Replaces #49234

Using `Test` suffix is deprecated since PHPUnit 10

Spotted in
* symfony/symfony#49233

Commits
-------

cb3db968e4 [PHPUnit 10] Use `TestCase` suffix for abstract tests in `/Tests/`

* 5.4:
  minor #49253 [PHPUnit 10] Use `TestCase` suffix for abstract tests in `/Tests/` (OskarStark)

* 5.4:
  Migrate to `static` data providers using `rector/rector`