Mark 1.52.1 as last release on github

[JeanCASPAR]

Currently, this is displayed
And users who click on that don't see 1.52.1 and that this is a fix.

[cuviper]

Perhaps it's because @rustbot didn't import the release notes for 1.52.1? cc @rust-lang/release

[Mark-Simulacrum]

I think I recall a conversation about this - I suspect we can fix it with a backport of the release notes to master and maybe some manual bumping.

[pietroalbini]

Backporting the release notes should do the trick. We should do that regardless of this issue too. I'll open a PR.

[pietroalbini]

Should be fixed by #85404!