ci: Fix pushing released images (#365)

Set `push: true` in Build and push image step.

This makes the following `docker push` commands
unnecessary, so have removed them.

Author: rblaine95

.github/workflows/release.yml

@@ -201,17 +201,11 @@ jobs:
         uses: docker/build-push-action@v6
         with:
           context: .
-          load: true
+          push: true
           file: docker/Dockerfile
           platforms: linux/amd64,linux/arm64
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
           cache-from: |
             type=gha,scope=docker-release-amd64
             type=gha,scope=docker-release-arm64
-
-      - name: Push image to GitHub Container Registry
-        run: docker image push --all-tags ghcr.io/${{ github.repository}}
-
-      - name: Push image to DigitalOcean Container Registry
-        run: docker image push --all-tags registry.digitalocean.com/${{ github.repository }}