new maintainers for guile libs

[Mike Gran]

Hello Guile community-

Well 2021 has been a strange time for me as it has been for many.  At
the beginning of 2021, I had the free time and the good health that
allowed me to imagine being a real contributer again, but, stuff has
changed.

So there are a few libraries in the Guile ecosystem I've worked on,
and I'm hoping someone else might be interested in owning them
henceforth.

Roughly in order of maintainability, from simple to complex, these are

- guile-aspell: a very simple binding to the Aspell spellcheck
  library. This would be an easy task, since it is a Guile-only
  binding with no C, and aspell rarely changes
- guile-curl: a C-based but straight-forward binding the the cURL API.
- guile-ncurses: a C-based binding for NCurses, libpanel, and libmenu.  It
  is a bit convoluted bcause the memory model for ncurses it iself
  quite strange.

Then there a couple of very obscure and little used libraries that I could
punt on, but, I don't really expect any interest

- guile-plotutils: draw plots in Guile using the plotutils backend
- zile-on-guile: a version of the zile editor, replacing its tiny LISP
  interpreter with Guile.

Guile-GI is a special case because at this point, I'm probably not the
prinmary contributor. But it could use more contributers and could use
a discussion about how to move it forward. I still hope to contribute
as I can.

So if anyone feels an affinity for any of this work, let me know.

I do hope to be more present in future, but, I'm not sure what the
future holds. Not sure if I will have the regular blocks of spare time
and energy that a maintainer-type figure needs.

And I do aplogize if anyone has been affected by my inaction.

Regards,
Mike Gran