BUG: Workaround GitHub app token expiration by explicitly setting push url

This address the following error reported after the built completes when
running the "Rebase onto origin/main before push" step.

```
fatal: could not read Username for 'https://github.com': No such device or address
```

Author: jcfr

.github/workflows/build-and-publish.yml

@@ -71,7 +71,7 @@ jobs:
           repository: Slicer/SlicerDocker
           path: SlicerDocker
           fetch-depth: 0
-          token: ${{ steps.app-token.outputs.token }}
+          persist-credentials: false
 
       - name: Update SlicerDocker and commit changes (if any)
         id: update-slicerdocker
@@ -124,6 +124,14 @@ jobs:
       # Only rebase & push when the repo actually changed.
       # NOTE: We DO NOT push on `force_build` because the intent is to rebuild/publish
 
+      - name: Prepare push credentials for SlicerDocker
+        if: steps.update-slicerdocker.outputs.updated == 'true'
+        working-directory: SlicerDocker
+        env:
+          APP_TOKEN: ${{ steps.app-token.outputs.token }}
+        run: |
+          git remote set-url origin https://x-access-token:${APP_TOKEN}@github.com/Slicer/SlicerDocker.git
+
       - name: Rebase onto origin/main before push
         if: steps.update-slicerdocker.outputs.updated == 'true'
         working-directory: SlicerDocker