Use 'tr' instead of 'node' for string lowercase operation (#1513)

Author: dleehr

.github/workflows/stage.yml

@@ -80,9 +80,11 @@ jobs:
           password: ${{ secrets.GITHUB_TOKEN }}
           registry: ghcr.io
 
+      # Image repository names must be lowercase, so get lowercase repo owner for ghcr.io
+      # See https://github.com/orgs/community/discussions/27086.
       - name: Lowercase github owner
         run: |
-          echo "OWNER=$(echo 'console.log("${{ github.repository_owner }}".toLowerCase())' | node -)" >> $GITHUB_ENV
+          echo "OWNER=$(echo $GITHUB_REPOSITORY_OWNER | tr '[:upper:]' '[:lower:]')" >> $GITHUB_ENV
 
       - name: Build container image
         run: |