Bump docker/build-push-action from 5 to 6 (#1316)

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 5 to 6.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v5...v6)

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

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

.github/workflows/docker_deployment.yml

@@ -42,7 +42,7 @@ jobs:
         name: Build and push stable release
         if: github.event_name == 'release'
         id: docker_build_release
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           push: true
           tags: molpopgen/fwdpy11:latest, molpopgen/fwdpy11:${{ github.event.release.tag_name }}
@@ -52,7 +52,7 @@ jobs:
       #   name: Build and push from main
       #   if: github.ref == 'refs/heads/main'
       #   id: docker_bfild_main
-      #   uses: docker/build-push-action@v5
+      #   uses: docker/build-push-action@v6
       #   with:
       #     push: true
       #     tags: molpopgen/fwdpy11:latest
@@ -62,7 +62,7 @@ jobs:
         name: Build image
         if: github.event_name == 'pull_request'
         id: docker_build_pull_request
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           push: false
           tags: molpopgen/fwdpy11:stable