Improve workflow format

Signed-off-by: Tommy <[email protected]>

.github/workflows/build.yml

@@ -15,6 +15,7 @@ on:
 env:
   REGISTRY: ghcr.io
   IMAGE_NAME: polarix-containers/nginx
+  TAG: latest
 
 jobs:
   build:
@@ -46,7 +47,7 @@ jobs:
         with:
           images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
           tags: |
-            latest
+            ${{ env.TAG }}
 
       - name: Build and push Docker image
         id: build-and-push
@@ -68,7 +69,7 @@ jobs:
       - name: Run Trivy vulnerability scanner
         uses: aquasecurity/trivy-action@master
         with:
-          image-ref: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          image-ref: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ env.TAG }}
           format: template
           template: '@/contrib/sarif.tpl'
           output: trivy-results.sarif
@@ -93,11 +94,11 @@ jobs:
         uses: anchore/scan-action@v4
         id: grype
         with:
-          image: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          image: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ env.TAG }}
           fail-build: false
 
       - name: Upload Grype scan results to GitHub Security tab
         uses: github/codeql-action/upload-sarif@v3
         with:
           sarif_file: ${{ steps.grype.outputs.sarif }}
-          category: grype
+          category: grype