investigate libc compatibility issue

[slingamn]

petteri reports the following error with v2.11.0:

golang /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.34' not found

I built the official binaries on Ubuntu 22.04, which ships glibc 2.35. It may be time to set CGO_ENABLED=0 on the official release binaries.

[slingamn]

https://utcc.utoronto.ca/~cks/space/blog/programming/GoAndGlibcVersioning

The release binaries do not even work in our own irc.ergo.chat production environment (Ubuntu 20.04); this probably requires a pointfix.

[slingamn]

For now, I rebuilt the binaries on a trusted Ubuntu 20.04 server, re-signed the checksums file, and re-uploaded them to Github. This restores parity with the previous release (v2.10.0).