Add a function for single line variables also

.github/workflows/ci.yaml

@@ -38,13 +38,14 @@ jobs:
         id: lowercase-variables
         shell: bash
         run: |
+          set_sl_var() { local f='%s=%s\n' ; printf -- "${f}" "$@" ; } ;
           for var in \
             actor='${{ github.actor }}' \
             repository_owner='${{ github.repository_owner }}'
           do
             k="$(cut -d '=' -f 1)"
             v="${var#${k}=}"
-            printf -- '%s=%s\n' -- >> "${GITHUB_OUTPUT}" \
+            set_sl_var >> "${GITHUB_OUTPUT}" \
               "${k}" "${v,,}"
           done
           unset -v k v var