changed Github actions to use branch name as tag

Author: mmahipal

.github/workflows/github-actions.yml

@@ -38,12 +38,14 @@ jobs:
       # extract branch name
       - name: Extract branch name
         if: github.event_name != 'pull_request'
-        run: BRANCH_NAME=${GITHUB_REF#refs/heads/}
+        env:
+          BRANCH_NAME: ${GITHUB_REF#refs/heads/}
 
       # extract branch name on pull request
       - name: Extract branch name
         if: github.event_name == 'pull_request'
-        run: BRANCH_NAME=${GITHUB_HEAD_REF}
+        env:
+          BRANCH_NAME: ${GITHUB_HEAD_REF}
 
       # Build and push Operator image (don't push on PR)
       - name: Build and push Docker image