chore: bump docker/build-push-action from 6.16.0 to 6.18.0

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 6.16.0 to 6.18.0.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v6.16.0...v6.18.0)

---
updated-dependencies:
- dependency-name: docker/build-push-action
  dependency-version: 6.18.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/release.yml

@@ -82,7 +82,7 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
       - name: "Build and push WebGoat"
-        uses: docker/build-push-action@v6.16.0
+        uses: docker/build-push-action@v6.18.0
         with:
           context: ./
           file: ./Dockerfile
@@ -95,7 +95,7 @@ jobs:
             webgoat_version=${{ env.WEBGOAT_MAVEN_VERSION }}
 
       - name: "Build and push WebGoat desktop"
-        uses: docker/build-push-action@v6.16.0
+        uses: docker/build-push-action@v6.18.0
         with:
           context: ./
           file: ./Dockerfile_desktop