Use ubuntu-latest for all CI runs

Author: svenluijten

.github/workflows/static.yml

@@ -71,7 +71,7 @@ jobs:
 
   composer-normalize:
     name: Composer Normalize
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
       - name: Setup PHP
         uses: shivammathur/setup-php@v2