Bump docker/build-push-action from 2.5.0 to 2.6.1

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 2.5.0 to 2.6.1.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](https://github.com/docker/build-push-action/compare/v2.5.0...v2.6.1)

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

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

.github/workflows/docker-build.yml

@@ -40,7 +40,7 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-docker-cpython-
       - name: Build and push
-        uses: docker/build-push-action@v2.5.0
+        uses: docker/build-push-action@v2.6.1
         with:
           context: .
           file: ./Dockerfile
@@ -81,7 +81,7 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-docker-pypy-
       - name: Build and push
-        uses: docker/build-push-action@v2.5.0
+        uses: docker/build-push-action@v2.6.1
         with:
           context: .
           file: ./pypy.Dockerfile
@@ -122,7 +122,7 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-docker-nginx-
       - name: Build and push
-        uses: docker/build-push-action@v2.5.0
+        uses: docker/build-push-action@v2.6.1
         with:
           context: .
           file: ./Dockerfile