Reshaping repo

The repo is designed for use with an existing builds.sr.ht service.
Besides lacking that, I am more interested in a containerized workflow
powered by a Makefile. Package source code will live in `pkgsrc/`,
packages will be built into `pkg/`, and packaging keys will be
generated into `keys/`.

Alos trimmed the packages down to what I will build.

py3-scmsrht: upgrade to 0.22.21

py3-scmsrht: upgrade to 0.22.17

py3-*: bump pkgrel for python rebuild

py3-scmsrht: remove nodejs-npm dependency

This is not required, and in any case was renamed by Alpine.

py3-scmsrht: upgrade to 0.22.9

sr.ht/py3-scmsrht: upgrade to 0.18.1

py3-srht, py3-scmsrht: update checksums

Update py3-srht & py3-scmsrht

Add builds.sr.ht as scm.sr.ht dependency

Fix archive URL for scm.sr.ht package

Add py3-scmsrht package, update py3-srht