Silently ignore .licenseignore and .license_header_template

Author: sebsto

.github/workflows/scripts/check-license-header.sh

@@ -40,7 +40,12 @@ fi
 
 paths_with_missing_license=( )
 
-file_paths=$(tr '\n' '\0' < .licenseignore | xargs -0 -I% printf '":(exclude)%" '| xargs git ls-files)
+file_excludes=".license_header_template
+.licenseignore"
+if [ -f .licenseignore ]; then 
+  file_excludes=$file_excludes\n$(cat .licenseignore)
+fi
+file_paths=$(echo "$file_excludes" | tr '\n' '\0' | xargs -0 -I% printf '":(exclude)%" '| xargs git ls-files)
 
 while IFS= read -r file_path; do
   file_basename=$(basename -- "${file_path}")