CI: Add condition to prevent building for sub-module releases

.github/workflows/docker-image.yml

@@ -11,6 +11,7 @@ env:
 
 jobs:
   build:
+    if: ${{ startsWith(github.ref, 'refs/tags/v') }}
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
@@ -65,6 +66,7 @@ jobs:
           retention-days: 1
 
   merge:
+    if: ${{ startsWith(github.ref, 'refs/tags/v') }}
     runs-on: ubuntu-latest
     needs:
       - build
@@ -102,6 +104,7 @@ jobs:
           docker buildx imagetools inspect ${{ env.REGISTRY_IMAGE }}:${{ steps.meta.outputs.version }}
   
   mirror:
+    if: ${{ startsWith(github.ref, 'refs/tags/v') }}
     runs-on: ubuntu-latest
     needs:
       - merge