Use operator.itemgetter for perf/readability in archive (#1764)

Co-authored-by: Martin Durant <martin.durant@alumni.utoronto.ca>

Author: Skylion007

fsspec/archive.py

@@ -1,3 +1,5 @@
+import operator
+
 from fsspec import AbstractFileSystem
 from fsspec.utils import tokenize
 
@@ -67,7 +69,7 @@ def ls(self, path, detail=True, **kwargs):
                     out = {"name": ppath, "size": 0, "type": "directory"}
                     paths[ppath] = out
         if detail:
-            out = sorted(paths.values(), key=lambda _: _["name"])
+            out = sorted(paths.values(), key=operator.itemgetter("name"))
             return out
         else:
             return sorted(paths)