build: changed use of github var in ci

Signed-off-by: Philip Windecker <philip.windecker@avenyr.de>

Author: philipwindecker

.github/workflows/antora-build.yml

@@ -39,7 +39,7 @@ jobs:
       working-directory: generator
       run: |
         echo "$GITHUB_REF_NAME"
-        sed -i -E "s/(branches\:) \[antora\/base-antora-setup\] \# osi-documentation/\1 [${GITHUB_REF_NAME}] \# osi-documentation/" site.yml
+        sed -i -E "s/(branches\:) \[antora\/base-antora-setup\] \# osi-documentation/\1 [$GITHUB_REF_NAME] \# osi-documentation/" site.yml
         cat site.yml
         sed -i -E "s/cd repo/cd generator/" run-build.sh
         cat run-build.sh