Style fix

Author: iarspider

process_pr.py

@@ -1336,7 +1336,7 @@ def process_pr(
         if cmssw_repo:
             # If there is a new package, add also a dummy "new" category.
             all_packages = set(itertools.chain.from_iterable(CMSSW_CATEGORIES.values()))
-            has_category = packages <= all_packages  # packages is-a-subset-of all_packages
+            has_category = packages.issubset(all_packages)
 
             if not has_category:
                 new_package_message = "\nThe following packages do not have a category, yet:\n\n"