```
graphics/py-traitsui: Update to 6.1.2 and add options for extra dependencies
* Update to 6.1.2 [1]
While I'm here:
* Add non-default options for the Python extra dependencies
* Hide the WXGTK option for Python 3 as the wx tookit isn't available for Python3, yet. (uses a similar approach as in rP503386 for www/py-autobahn)
Changelog:
https://github.com/enthought/traitsui/blob/6.1.1/CHANGES.txt
PR: 238469
Submitted by: vladimir.chukharev@gmail.com (maintainer) [1]
Reviewed_by: koobs
Differential_Revision: D21229
```