[issue44498] add deprecation warnings for asynchat, asyncore and smtpd

[miss-islington]

Change by miss-islington <mariatta.wijaya+miss-islington at gmail.com>:


----------
nosy: +miss-islington
nosy_count: 6.0 -> 7.0
pull_requests: +25480
pull_request: https://github.com/python/cpython/pull/26904

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue44498>
_______________________________________