Deprecation warning when using `pip_api` on Python 3.11

[jamesclark-Zapata]

Reproduction

python3.11 -Wall  -c "import pip_api"
<snip>/lib/python3.11/site-packages/pip_api/_vendor/pyparsing.py:108: DeprecationWarning: module 'sre_constants' is deprecated
  import sre_constants

Root cause sre_constants is imported by the vendored pyparsing module: https://github.com/di/pip-api/blob/5ac3ec840dd4eb0fd20ea69d5d2362472e0d4daf/pip_api/_vendor/pyparsing.py#L108

see: https://github.com/python/cpython/issues/91308

[di]

I took a shot at this in https://github.com/di/pip-api/pull/196 but ran up against some unexpected test failures and haven't had a chance to take a closer look yet.