Bump docker/build-push-action from 2 to 6

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 2 to 6.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v2...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>

Author: dependabot[bot]

.github/workflows/docker.yml

@@ -62,7 +62,7 @@ jobs:
             type=semver,pattern={{major}},enable=${{ !startsWith(github.ref, 'refs/tags/0.') }}
 
       - name: Build and export to Docker (linux/amd64)
-        uses: docker/build-push-action@v2
+        uses: docker/build-push-action@v6
         with:
           context: .
           platforms: linux/amd64
@@ -72,7 +72,7 @@ jobs:
           cache-to: type=gha,mode=max
 
       - name: Build and export to Docker (linux/arm64)
-        uses: docker/build-push-action@v2
+        uses: docker/build-push-action@v6
         with:
           context: .
           platforms: linux/arm64
@@ -82,7 +82,7 @@ jobs:
           cache-to: type=gha,mode=max
 
       - name: Build and export to Docker (linux/arm/v7)
-        uses: docker/build-push-action@v2
+        uses: docker/build-push-action@v6
         with:
           context: .
           platforms: linux/arm/v7
@@ -98,7 +98,7 @@ jobs:
           docker run --rm ${{ env.TEST_IMAGE }}:armv7 php --version
 
       - name: Build and push Docker image
-        uses: docker/build-push-action@v2.7.0
+        uses: docker/build-push-action@v6
         with:
           context: .
           platforms: ${{ env.PLATFORMS }}