HGKeeper

Disable the old TextBuffer serialization formats for the time being.
gtk4
2022-01-31, Gary Kramlich

a5047abeede9

Disable the old TextBuffer serialization formats for the time being.

We'll come back and port these to Gdk.ContentSerializeFunc's after we get
everything else working.

Testing Done:
Compiled and verified the warnings were gone.

Reviewed at https://reviews.imfreedom.org/r/1267/

Talkatu is versioned in [mercurial](https://www.mercurial-scm.org/) and is

available on [keep.imfreedom.org](https://keep.imfreedom.org/talkatu/talkatu).

All contributions are provided via review requests at [reviews.imfreedom.org](https://reviews.imfreedom.org/).