Replace deprecated command with environment file (kubernetes#2088)

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

Author: jongwooo

.github/workflows/release-cpo.yaml

@@ -29,7 +29,7 @@ jobs:
 
     - name: Get the version from ref
       id: get_version
-      run: echo ::set-output name=VERSION::${GITHUB_REF/refs\/tags\//}
+      run: echo VERSION=${GITHUB_REF/refs\/tags\//} >> $GITHUB_OUTPUT
 
     - name: build & publish images
       run: |