Fix gtihub workflow docker_tag

Author: ababak

.github/workflows/docker-image.yml

@@ -23,7 +23,7 @@ jobs:
       - name: Set output variables
         id: vars
         run: |
-          echo "DOCKER_TAG=$('${{ github.ref_name }}' -replace '^v', '' -replace '\.\w+$', '')" >> $GITHUB_OUTPUT
+          echo "DOCKER_TAG=$('${{ github.ref_name }}' -replace '^v', '' -replace '\.\w+$', '')" >> "$GITHUB_OUTPUT"
 
       - name: Build Docker image
         run: docker build . --file Dockerfile --tag ababak/cgcpp:${{ steps.vars.outputs.DOCKER_TAG }}