formatting fix

Author: mr-c

cwltool/job.py

@@ -473,9 +473,7 @@ def _preserve_environment_on_containers_warning(
     def extract_environment(
         runtimeContext: RuntimeContext, envVarReq: Mapping[str, str]
     ) -> Mapping[str, str]:
-        """
-        Extract environment variables that should be preserved
-        """
+        """Extract environment variables that should be preserved."""
         # Start empty
         env: dict[str, str] = {}
         # Preserve any env vars