Removal proposal: py-blockdiag py-nwdiag py-seqdiag py-actdiag

[Adam <adam%netbsd.org@localhost>]

I would like to remove py-blockdiag, py-nwdiag, py-seqdiag, and py-actdiag from graphics. These don't work with recent Python versions. There is a ticket open upstream:

https://github.com/blockdiag/blockdiag/issues/186

but the development seems to be abandoned - last commit has been done 5 years ago.

The packages are not required by anything else.

If no one objects, I'll do the termination by the end of this week.

Kind regards,
Adam