gh-137440: Update comment in Python/hamt.c on importing for testing (GH-137441)
Switch from `_testcapi` to `_testinternalcapi`.
(cherry picked from commit
7ab68cd50658f76abc9e0f12e6212736e2440720)
Co-authored-by: Bartosz Sławecki <bartosz@ilikepython.com>
=====
The HAMT datatype is accessible for testing purposes under the
-`_testcapi` module:
+`_testinternalcapi` module:
- >>> from _testcapi import hamt
+ >>> from _testinternalcapi import hamt
>>> h = hamt()
>>> h2 = h.set('a', 2)
>>> h3 = h2.set('b', 3)