Bump wxPython version to support newer python versions

[lekv]

I noticed that wxPython couldn't be installed as a dependency with Python 3.12 on MacOS. It failed with the following error message:

ModuleNotFoundError: No module named 'attrdict'

After consulting wxWidgets/Phoenix#2296, I found out that this was an issue with wxPython and confirmed that 4.2.1 works. I tested this locally.

Fixes #10577

This also fixes #10577, presumably because wxPython now correctly requires attrdict3. I confirmed that the following steps now work:

$ rm -rf venv
$ python3.12 -mvenv venv
$ source venv/bin/activate
$ pip install -r requirements.txt

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[lekv]

@kk7ds — please let me know if you'd prefer I open a new bug. The issue and fix are related to https://chirpmyradio.com/issues/10577 but one could argue the are different things.

[kk7ds]

I'm haven't bumped yet because of this: wxWidgets/Phoenix#2499 .. Hoping for a newer release with a fix at some point. However, right now the macOS builds are done with 3.10 and 4.2.0 and I want to keep these requirements in sync. The window-opens-behind bug is incredibly annoying.

But yeah, if you prefer you can just manually install 4.2.1 locally, obviously, if the python version is more important to you.