[3.13] gh-142651: make `Mock.call_count` thread-safe (GH-142656) (#142744)

gh-142651: make `Mock.call_count` thread-safe (GH-142656)
(cherry picked from commit 850f95f6f64a55920cbb91b022b70b736bd20ed8)

Co-authored-by: chaope <pengchaoandy@gmail.com>