Bump docker/build-push-action from 6.5.0 to 6.13.0

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 6.5.0 to 6.13.0.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v6.5.0...v6.13.0)

---
updated-dependencies:
- dependency-name: docker/build-push-action
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/build.yaml

@@ -39,7 +39,7 @@ jobs:
             ghcr.io/svthalia/concrexit
 
       - name: Build and push Docker image
-        uses: docker/build-push-action@v6.5.0
+        uses: docker/build-push-action@v6.13.0
         with:
           context: ./
           file: ./infra/concrexit/Dockerfile
@@ -83,7 +83,7 @@ jobs:
             ghcr.io/svthalia/concrexit-nginx
 
       - name: Build and push Docker image
-        uses: docker/build-push-action@v6.5.0
+        uses: docker/build-push-action@v6.13.0
         with:
           context: ./infra/nginx
           push: true