[BUG] urwid warns for its own import

[Julian]

Description:

Importing urwid produces a deprecation warning saying not to import urwid.wimp -- but it's imported by urwid itself :)

Affected versions (if applicable)

• master branch (b79afaf)
• Latest stable version from pypi

Steps to reproduce (if applicable)

python3.11 -m venv venv; venv/bin/python -m pip install --quiet urwid && venv/bin/python -W error -c 'import urwid'

Expected/actual outcome

Produces:

⊙  python3.11 -m venv venv; venv/bin/python -m pip install --quiet urwid && venv/bin/python -W error -c 'import urwid'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/Users/julian/Desktop/venv/lib/python3.11/site-packages/urwid/__init__.py", line 76, in <module>
    from urwid.event_loop import AsyncioEventLoop, EventLoop, ExitMainLoop, MainLoop, SelectEventLoop
  File "/Users/julian/Desktop/venv/lib/python3.11/site-packages/urwid/event_loop/__init__.py", line 7, in <module>
    from .main_loop import MainLoop
  File "/Users/julian/Desktop/venv/lib/python3.11/site-packages/urwid/event_loop/main_loop.py", line 36, in <module>
    from urwid.wimp import PopUpTarget
  File "/Users/julian/Desktop/venv/lib/python3.11/site-packages/urwid/wimp.py", line 17, in <module>
    warnings.warn(
DeprecationWarning: 'urwid.wimp' is not expected to be imported directly. Please use public access from "urwid" package. Module 'urwid.wimp' is deprecated and will be removed in the future.