Bump docker/build-push-action from 5 to 6

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](https://github.com/docker/build-push-action/compare/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>

.github/workflows/dockerimage.yml

@@ -47,7 +47,7 @@ jobs:
             ${{ runner.os }}-buildx-
 
       - name: Build squid image
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: .
           push: false
@@ -75,7 +75,7 @@ jobs:
           sed -i "s%FROM b4tman/squid%FROM $TEST_TAG%" ssl-bump/Dockerfile
       
       - name: Build 'ssl-bump' image
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: .
           push: false
@@ -174,7 +174,7 @@ jobs:
           password: ${{ secrets.CR_PAT }}
 
       - name: Build squid image
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: .
           push: true
@@ -193,7 +193,7 @@ jobs:
           mv /tmp/.buildx-cache-new /tmp/.buildx-cache
 
       - name: Build 'ssl-bump' image
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: ssl-bump
           push: true
@@ -213,7 +213,7 @@ jobs:
           mv /tmp/.buildx-cache-new /tmp/.buildx-cache
 
       - name: Build 'ssl-bump' image for ghcr
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: ssl-bump
           push: true