Ignore a style warning from bugbear.

Creating lots of RefResolvers shouldn't be common (as creating lots
of Validators should be reasonably uncommon itself), and even if
one did so, we have a fixed size LRU cache, so this seems OK.

Refs: PyCQA/flake8-bugbear#218

jsonschema/validators.py

@@ -802,7 +802,7 @@ def resolving(self, ref):
     def _find_in_referrer(self, key):
         return self._get_subschemas_cache()[key]
 
-    @lru_cache()
+    @lru_cache()  # noqa: B019
     def _get_subschemas_cache(self):
         cache = {key: [] for key in _SUBSCHEMAS_KEYWORDS}
         for keyword, subschema in _utils.search_schema(
@@ -811,7 +811,7 @@ def _get_subschemas_cache(self):
             cache[keyword].append(subschema)
         return cache
 
-    @lru_cache()
+    @lru_cache()  # noqa: B019
     def _find_in_subschemas(self, url):
         subschemas = self._get_subschemas_cache()["$id"]
         if not subschemas: