Upgrade server to v0.7.2
Limit maximum workers to 9

The 9 is maximum because each worker uses database pool connection in
damn server. The database pool of asyncpg [1] has by default min/max
number of connection set up to 10. The PostgreSQL [2] database has the
default of 100 maximum connections. So, 9 x 10 = 90 < 100, there is 10
connections backup (for admin connections or so on.)

[1]: https://magicstack.github.io/asyncpg/current/index.html
[2]: https://www.postgresql.org/
Upgrade client to v0.12.1
Upgrade server to v0.7.1
Merge branch 'add-www'
Update changelog
Add server setup introduction
Add docker www service
Solve redirection to https in traefik labels
Switch link to mailing list for the list address
Merge branch 'release/0.8.0'
Update changelog
Merge branch 'move-to-sr.ht'
Update changelog
Add upgrade to v0.8.0 section
Fix domain name variable in clients
Clear up upgrade/update sytax
Overwrite systemd config files if exists
Include chat to default systemd config file
Reformat readme
Remove contribution section, add mailing list