Merge updated AppVeyor configuration for new bugs and updated packages

[RedFantom]

This PR includes the following AppVeyor fixes:

• A work-around for https://github.com/msys2/MSYS2-packages/issues/2589
• Updated package versions The MSYS2 repositories keep only few old versions of packages, so the ones previously used are no longer available.
• The pacman package work-around is disabled (no longer needed)

TODO:

• [ ] Investigate and fix the execution of cmake (https://github.com/TkinterEP/python-tksvg/blob/master/setup.py#L64)

As requested in PR #1 .

[rdbende]

The upstream now has working CI build on Github Actions: https://github.com/oehhar/tksvg/releases/tag/0.13 I think we could just use that CI and release the wheels to Pypi. That would make installing this much easier.

Edit: Yeah, I realized, there are wheels on Pypi (for Windoze and Linux), but the setup.py for example could be much simpler.

[Moosems]

Soooo.....

[rdbende]

Superseeded by #6