github-ci: fix git refs/heads paths mistakes

Found that in previous commit to debian_11.yml file were made mistakes
in git refs/heads paths:

  e0a33ffe ("github-ci: build packages for debian-bullseye")

This patch fixes it.

Follows up #5638

.github/workflows/debian_11.yml

@@ -33,9 +33,9 @@ jobs:
           GPG_SIGN_KEY: ${{ secrets.GPG_SIGN_KEY }}
         run: |
           if ${{ github.event_name == 'push' &&
-              ( github.ref == 'ref/head/master' ||
-                github.ref == 'ref/head/1.10' ||
-                startsWith(github.ref, 'refs/head/2.') ||
+              ( github.ref == 'refs/heads/master' ||
+                github.ref == 'refs/heads/1.10' ||
+                startsWith(github.ref, 'refs/heads/2.') ||
                 startsWith(github.ref, 'refs/tags') ) }} ; then
             sudo apt-get -y update
             sudo apt-get install -y procmail createrepo awscli reprepro