images/freebsd: upgrade 11.x to 11.3
Use srht.flask.session instead of flask.session
Use --allow-releaseinfo-change in Debian genimg
Update Debian stable & testing
Add Debian bullseye
Fix clone URLs which end in .git
handle SSH connection strings properly
Fix a small typo.
Support setting the name of a directory to clone a repo into

This is necessary for supporting forks with a renamed repository in
dispatch.sr.ht, as the 'cd' statements in the manifest would be
incorrect otherwise.
worker: check for SetTaskStatus error once

Otherwise, if the worker pg user doesn't have UPDATE privileges on the
task table, the error will go unnoticed.
Upgrade to Alpine 3.10
worker: test db connection before starting worker

Without this, a misconfigured database string would not be noticed
(immediately), but now the worker aborts directly if it can't access the
Fetch submodules regardless of whether the repo has a ref attached

Since 20aa65c0ee, instead of cloning with --recursive, submodules are
updated after the correct ref is checked out. However, it was doing so
*only* when a ref is specified.
Update latest Alpine version
Update Arch Linux package signing key
Remove Fedora 28 support (EoL)
Add environment to config.example.ini
images/freebsd: mount devfs before chrooting

Thsi fixes build failures due to pkg not finding /dev/null. See [1].

[1]: https://github.com/freebsd/pkg/issues/1763#issuecomment-502579057
Increase size of Arch & Fedora images