Update the existing pre-commit hook

This was updated mechanically using the following command:

```
pre-commit autoupdate
```

Author: kurtmckee

.pre-commit-config.yaml

@@ -10,7 +10,7 @@ repos:
       - id: check-hooks-apply
 
   - repo: https://github.com/asottile/pyupgrade
-    rev: v2.19.0
+    rev: v3.20.0
     hooks:
       - id: pyupgrade
         args: ["--py36-plus"]