fix env combine

Author: yaozheng-fang

.github/workflows/push-preview-image-to-vecr.yaml

@@ -53,7 +53,7 @@ jobs:
       # Specify a platform, as VeFaaS required `linux/amd64`
       - name: Build and push
         run: |
-          IMAGE_TAG=${{ env.CR_URL }}/${{ env.CR_NAMESPACE }}/${{ env.CR_REPO }}:preview
+          IMAGE_TAG=$CR_URL/$CR_NAMESPACE/$CR_REPO:preview
           docker buildx build \
             --file $DOCKERFILE \
             --tag $IMAGE_TAG \

.github/workflows/push-stable-image-to-vecr.yaml

@@ -55,8 +55,8 @@ jobs:
       # push 2 tags (x.x.x and latest) in one push
       - name: Build and push
         run: |
-          LATEST_TAG: ${{ env.CR_URL }}/${{ env.CR_NAMESPACE }}/${{ env.CR_REPO }}:latest
-          VERSION_TAG: ${{ env.CR_URL }}/${{ env.CR_NAMESPACE }}/${{ env.CR_REPO }}:${{ github.ref_name }}
+          LATEST_TAG=$CR_URL/$CR_NAMESPACE/$CR_REPO:latest
+          VERSION_TAG=$CR_URL/$CR_NAMESPACE/$CR_REPO:$GITHUB_REF_NAME
           docker buildx build \
             --file $DOCKERFILE \
             --tag $VERSION_TAG \