ci: update workflow

.github/workflows/main.yml

@@ -45,20 +45,20 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Build Docker image
-        run: docker build -t $IMAGE:latest .
+        run: docker build -t ${IMAGE}:latest .
 
       - name: Save Docker image as tar file
-        run: docker save -o $IMAGE.tar $IMAGE:latest
+        run: docker save -o ${IMAGE}.tar ${IMAGE}:latest
       - name: Transfer Docker image to remote server
         run: |
           mkdir -p ~/.ssh
           echo "${{ secrets.SSH_KEY }}" > ~/.ssh/id_rsa
           chmod 600 ~/.ssh/id_rsa
-          scp -o StrictHostKeyChecking=no $IMAGE.tar ${{ secrets.SSH_USERNAME }}@${{ secrets.SSH_HOST }}:${{ secrets.REMOTE_PATH }}
+          scp -o StrictHostKeyChecking=no ${IMAGE}.tar ${{ secrets.SSH_USERNAME }}@${{ secrets.SSH_HOST }}:${{ secrets.REMOTE_PATH }}
       - name: Load Docker image on remote server
         run: |
           ssh -o StrictHostKeyChecking=no ${{ secrets.SSH_USERNAME }}@${{ secrets.SSH_HOST }} << 'ENDSSH'
-          docker load -i ${{ secrets.REMOTE_PATH }}/$IMAGE.tar
+          docker load -i ${{ secrets.REMOTE_PATH }}/${IMAGE}.tar
           ENDSSH
       - name: Transfer Docker Compose file to remote server
         run: |