add pyupgrade pre-commit hook
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 3a341a8..a982b5f 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,4 +1,9 @@
 repos:
+  - repo: https://github.com/asottile/pyupgrade
+    rev: v1.26.2
+    hooks:
+      - id: pyupgrade
+        args: ["--py36-plus"]
   - repo: https://github.com/asottile/reorder_python_imports
     rev: v1.9.0
     hooks: