Adding the env. variable with correct name

.github/workflows/build-push.yml

@@ -11,6 +11,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
+    - name: Set Image name
+      run: |
+        echo "IMAGE_NAME=k2patel/rtorrent:latest" >> $GITHUB_ENV
+
     - name: Checkout code
       uses: actions/checkout@v4
 
@@ -23,8 +27,7 @@ jobs:
     - name: Build the Docker image
       id: build
       run: |
-        docker build . -t k2patel/postfix:latest
-        echo "IMAGE_NAME=k2patel/postfix:latest" >> $GITHUB_ENV
+        docker build . -t ${{ env.IMAGE_NAME }}:latest
 
     - name: Push the Docker image
       run: docker push ${{ env.IMAGE_NAME }}