build: release posts the release tag and points :latest to it

Author: deanq

.github/workflows/CD-docker_release.yml

@@ -31,4 +31,6 @@ jobs:
         uses: docker/build-push-action@v4
         with:
           push: true
-          tags: ${{ vars.DOCKERHUB_REPO }}/${{ vars.DOCKERHUB_IMG }}:${{ github.event.release.tag_name }}
+          tags: |
+            ${{ vars.DOCKERHUB_REPO }}/${{ vars.DOCKERHUB_IMG }}:${{ github.event.release.tag_name }}
+            ${{ vars.DOCKERHUB_REPO }}/${{ vars.DOCKERHUB_IMG }}:latest