Support MacOS 12

[btaczala]

MacOS 12 removes support for python (2.7) and no longer ships any
python.
In order properly support newer MacOS releases pass workflow should
reuse python manually installed (ideally via brew)

[jmcphers]

Just ran into this myself, all working well after manually applying your change! Thanks for doing this.

[chipsenkbeil]

@btaczala I know that you installed python3 using brew, which I assume placed it in /usr/local/bin/python3.

On Mac 12.3+, I think there's a stub for python3 located at /usr/bin/python3. It doesn't work out of the box, but when you first run it you get a prompt to install XCode Developer Tools, which then installs Python3 at that location.

Regardless of where it is located, is there a reason your PR includes a hardcoded path to python3 in the info.plist instead of just updating from python to python3?

[CGenie]

Is anyone willing to take over this repo? I don't use a Mac anymore and I see the code is useful to people, would be nice to keep things up-to-date.