Update doc/build_antora.sh

Co-authored-by: Copilot <[email protected]>

Author: jll63

doc/build_antora.sh

@@ -34,7 +34,7 @@ elif [ -n "${GITHUB_REPOSITORY:-}" ]; then
   sha=${GITHUB_SHA}
 fi
 
-if [ -n "${repository}" ] && -n "${sha}" ]; then
+if [ -n "${repository}" ] && [ -n "${sha}" ]; then
   base_url="https://github.com/${repository}/blob/${sha}"
   echo "Setting base-url to $base_url"
   cp mrdocs.yml mrdocs.yml.bak