meta.sr.ht: move .billing location

prometheus: upgrade to 2.15.1

sr.ht/py3-weasyprint: upgrade to v51

sr.ht/mercurial: bump pkgrel

sr.ht/py3-pygit2: new aport

sr.ht/hg-evolve: bump pkgrel

py3-srht: add html5lib dependency

man.sr.ht: add py3-scmsrht dependency

Add py3-redis to py3-srht dependencies

Add more version upgrade tips

sr.ht/meta.sr.ht: add -billing subpackage

Update README.md with upgrade lessons

builds.sr.ht: bump pkgrel

dispatch.sr.ht: upgrade to 0.13.2

sr.ht/git-send-email.io: update to 0.1.9

paste.sr.ht: bump pkgrel

sr.ht/paste.sr.ht: upgrade to 0.9.0

sr.ht/builds.sr.ht: update to 0.52.4

sr.ht/py3-scmsrht: upgrade to 0.18.1

sr.ht/py3-srht: upgrade to 0.57.2