build: revert update to latest checkout action

The latest checkout v6 action is causing the docs
publish to fail. Until we resolve the issue,
revert back to v5.

Signed-off-by: Travis Nielsen <tnielsen@redhat.com>

.github/workflows/push-build.yaml

@@ -15,7 +15,7 @@ defaults:
 permissions:
   contents: read
   packages: write
-  id-token: write  # for cosign OIDC keyless signing
+  id-token: write # for cosign OIDC keyless signing
 
 jobs:
   push-image-to-container-registry:
@@ -23,7 +23,7 @@ jobs:
     if: github.repository == 'rook/rook'
     steps:
       - name: checkout
-        uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
         with:
           fetch-depth: 0