Add webhooks init script to meta.sr.ht

Add -openrc, fix sources for meta.sr.ht

Update man.sr.ht.post-upgrade

Also moves alembic dependency to py3-srht

Add py3-prometheus-client to meta.sr.ht deps

Remove default alembic config

It's broken anyway

Do not install example config with meta.sr.ht

Rename meta.sr.ht init script

Update meta.sr.ht to latest version

Package meta.sr.ht