chore(deps): update precommit hook asottile/pyupgrade to v2.21.0 (#308)

Co-authored-by: Renovate Bot <[email protected]>

Author: renovate[bot]

.pre-commit-config.yaml

@@ -65,7 +65,7 @@ repos:
         args: [--py3-plus]
         exclude: nonunicode/.*
 -   repo: https://github.com/asottile/pyupgrade
-    rev: v2.20.0
+    rev: v2.21.0
     hooks:
     -   id: pyupgrade
         args: [--py3-plus]