[Python] Unable to install Tkinter with pyenv Python instances on macOS

Versions of Python installed via pyenv fail to import tkinter:

※ python
Python 3.8.1 (default, Feb 29 2020, 11:45:59)
[Clang 11.0.0 (clang-1100.0.33.17)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import tkinter
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/factor/.pyenv/versions/3.8.1/lib/python3.8/tkinter/__init__.py", line 36, in <module>
import _tkinter # If this fails your Python may not be configured for Tk
ModuleNotFoundError: No module named '_tkinter'
>>>


Or you might get a message about the header version doesn't match the binary:

DEPRECATION WARNING: The system version of Tk is deprecated and may be removed in a future release. Please don't rely on it. Set TK_SILENCE_DEPRECATION=1 to suppress this warning.
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/factor/.pyenv/versions/3.8.1/lib/python3.8/tkinter/__init__.py", line 4552, in _test
root = Tk()
File "/Users/factor/.pyenv/versions/3.8.1/lib/python3.8/tkinter/__init__.py", line 2263, in __init__
self._loadtk()
File "/Users/factor/.pyenv/versions/3.8.1/lib/python3.8/tkinter/__init__.py", line 2279, in _loadtk
raise RuntimeError("tk.h version (%s) doesn't match libtk.a version (%s)"
RuntimeError: tk.h version (8.6) doesn't match libtk.a version (8.5)

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