Advertize PostgreSQL 13, prep for Bullseye support

[alexmv]

#17170 added support for these, but not documentation. We should add them to the list of documented versions that Zulip supports.

[zulipbot]

Hello @zulip/server-production members, this issue was labeled with the "area: documentation (production)" label, so you may want to check it out!

[timabbott]

Ubuntu Groovy support is only for the development environment. I guess the Postgres 13 support is probably real, but I'm not sure we've actually tested it at all?

I'm not sure how useful it is to document Groovy -- it reaches EOL in July (2-3 months from now). I think it's reasonable to have a policy of not bothering to document Ubuntu non-LTS releases given how short their support lifetime is?

@ligmitz FYI.

[ligmitz]

Yeah, non-LTS releases have a life support of about 9 months only, so I think it is not quite useful to give production support for them (due to short life). The Zulip support for Groovy is only for development. We added support for Debian Bullseye recently but it is not documented here, should we document that as a supported platform there now?

[alexmv]

#18271 swaps the default production PostgreSQL to 13, and thus tests it as well as upgrades to it. Not documenting Groovy makes sense to me, given its short support schedule. Documenting Bullseye should probably wait until it's actually officially released, I think? But we can prep a PR that makes it easy to merge as soon as it does.

[timabbott]

@alexmv this was fixed by #18271, right?

[alexmv]

I think the only thing to possibly do is decide if we're advertizing Bullseye in 4.0, or holding off until it gets a release. I think I'm in favor of "it will work when it's released, even if we don't list it; we can start officially listing it in 4.1 if it doesn't go out by 4.0 final."

[timabbott]

Yeah, I think that policy makes sense to me, especially since it doesn't actually work without an /etc/os-release that will only be normal once it is released.