test: unpin Ubuntu, use latest

pierreprinetti · pierreprinetti · commit c19d1713377b · 2021-12-10T15:49:15.000+01:00
diff --git a/.github/workflows/unit.yml b/.github/workflows/unit.yml
@@ -2,7 +2,7 @@ on: [push, pull_request]
 name: Unit Testing
 jobs:
   test:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
