dispatch.sr.ht: upgrade to 0.15.8

builds.sr.ht: upgrade to 0.66.4

py3-srht: upgrade to 0.67.0

py3-arrow: remove; now in alpine community

py3-weasyprint: python 3.9 fixes

py3-vine: "fix" test suite

py3-unidiff: fix tests

py3-pgpy: add wheel dependency

py3-iso3166: fix tests

py3-colour: add missing dependency

py3-cairocffi: remove; now in alpine community

py3-cairosvg: remove; now in alpine community

py3-tinycss2: remove; now in alpine community

py3-cssselect2: remove; now in alpine community

py3-celery: remove obsolete dependency

py3-cairocffi: new dependency

builds.sr.ht: new dependency

py3-ansi2html: fix dependencies

py3-billiard: "upgrade" to 3.6.4.0

submit-builds: rename config variable