Correct tag syntax and only push latest on a push to master

.github/workflows/main.yml

@@ -52,5 +52,13 @@ jobs:
         with:
           context: ./${{ matrix.component }}
           file: Dockerfile
-          tags: ghcr.io/ekimekim/wubloader-${{ matrix.component }}:$TAG,ghcr.io/ekimekim/wubloader-${{ matrix.component }}:latest
+          tags: ghcr.io/ekimekim/wubloader-${{ matrix.component }}:${{ env.TAG }}
           push: true
+
+      - name: Build ${{ matrix.component }} latest
+        uses: docker/build-push-action@v2.7.0
+        if: github.event_name != 'pull_request' and github.ref == 'refs/heads/master'
+        with:
+          context: ./${{ matrix.component }}
+          file: Dockerfile
+          tags: ghcr.io/ekimekim/wubloader-${{ matrix.component }}:latest