Make precommit checks happy (#5751)

tests/unit_tests/test_cpp_generator.py

@@ -1,4 +1,4 @@
-from typing import Iterator
+from collections.abc import Iterator
 
 import math
 

tests/unit_tests/test_cpp_helpers.py

@@ -1,5 +1,5 @@
 import pytest
-from mock import Mock
+from unittest.mock import Mock
 
 from esphome import cpp_helpers as ch
 from esphome import const