gha: Bump deprecated GHA workflow dependencies

Deprecation notice:
https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Changelogs (no entries relevant to us):
  * https://github.com/docker/setup-buildx-action/releases/tag/v4.0.0
  * https://github.com/docker/build-push-action/releases/tag/v7.0.0
  * https://github.com/actions/cache#v5

.github/actions/run-in-docker-action/action.yml

@@ -13,9 +13,9 @@ inputs:
 runs:
   using: "composite"
   steps:
-    - uses: docker/setup-buildx-action@v3
+    - uses: docker/setup-buildx-action@v4
 
-    - uses: docker/build-push-action@v6
+    - uses: docker/build-push-action@v7
       id: main_builder
       continue-on-error: true
       with:
@@ -24,7 +24,7 @@ runs:
         load: true
         cache-from: type=gha,scope=${{ inputs.scope }}
 
-    - uses: docker/build-push-action@v6
+    - uses: docker/build-push-action@v7
       id: retry_builder
       if: steps.main_builder.outcome == 'failure'
       with: