[3.7] bpo-32746: Fix multiple typos (GH-5144) (GH-5520)

Fix typos found by codespell in docs, docstrings, and comments.
(cherry picked from commit c3d9508ff22ece9a96892b628dd5813e2fb0cd80)

Co-authored-by: Leo Arias <leo.arias@canonical.com>
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 4a33f2d..b69fcdf 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -3420,7 +3420,7 @@
     PyErr_SetString(PyExc_ValueError, "fromutc: tz.dst() gave"
                     "inconsistent results; cannot convert");
 
-    /* fall thru to failure */
+    /* fall through to failure */
 Fail:
     Py_XDECREF(off);
     Py_XDECREF(dst);