Bump docker/build-push-action from 3 to 4 (#30)

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 3 to 4.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v3...v4)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/docker.yml

@@ -73,7 +73,7 @@ jobs:
           password: ${{ secrets.docker_password }}
 
       - name: Build Cryptobox
-        uses: docker/build-push-action@v3
+        uses: docker/build-push-action@v4
         with:
           file: dockerfiles/Dockerfile
           context: .
@@ -84,7 +84,7 @@ jobs:
           push: ${{ inputs.publish }}
 
       - name: Build Runtime
-        uses: docker/build-push-action@v3
+        uses: docker/build-push-action@v4
         with:
           file: dockerfiles/Dockerfile
           context: .