Add .pre-commit-config.yaml file (#42)

This should make pre-commit.ci work.

.pre-commit-config.yaml

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
new file mode 100644
index 0000000..7a2e2f1
--- /dev/null
+++ b/.pre-commit-config.yaml
@@ -0,0 +1,5 @@
+repos:
+-   repo: https://github.com/PyCQA/flake8
+    rev: 6.0.0
+    hooks:
+    -   id: flake8