[FIX] Use ubuntu-latest on GitHub Actions

The "Publish new version to TER"-job used not available Ubuntu 20.04.

Author: dkd-kaehm

.github/workflows/ci.yml

@@ -159,7 +159,7 @@ jobs:
     name: Publish new version to TER
     needs: tests
     if: startsWith(github.ref, 'refs/tags/')
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     env:
       TYPO3_API_TOKEN: ${{ secrets.TYPO3_API_TOKEN }}