Update workflow_approval job

Author: Kawron

.github/workflows/ci_build_test.yaml

@@ -23,7 +23,7 @@ permissions:
 jobs:
   workflow_approval:
     name: Approve workflow
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     environment: workflow-approval
     steps:
       - name: Approve workflow