ci: GHA basic format & pre-commit (#2309)

diff --git a/tests/test_copy_move.py b/tests/test_copy_move.py
index 0e671d9..6b53993 100644
--- a/tests/test_copy_move.py
+++ b/tests/test_copy_move.py
@@ -1,3 +1,4 @@
+# -*- coding: utf-8 -*-
 import pytest
 from pybind11_tests import copy_move_policies as m