BAU: Bump buildx and build-push actions

The new versions use Node.js 24. Dependabot would have updated it
automatically, but we may as well do it while working on this file.

Author: whi-tw

.github/workflows/reusable-review_apps_on_pr_change.yml

@@ -45,10 +45,10 @@ jobs:
           echo "URI=${BASE_URI}-${HEAD_SHA}-$(date +%s)" >> "$GITHUB_OUTPUT"
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3.12.0
+        uses: docker/setup-buildx-action@4d04d5d9486b7bd6fa91e7baf45bbb4f8b9deedd # v4.0.0
 
       - name: Build
-        uses: docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83 # v6.18.0
+        uses: docker/build-push-action@d08e5c354a6adb9ed34480a06d141179aa583294 # v7.0.0
         with:
           push: true
           tags: ${{ steps.generate_image_uri.outputs.URI }}