You can download 13.1 here: https://developer.apple.com/download/all/ Just scroll down. FWIW: I've reinstalled 13.2 several times now, each time the problem goes away for a while and then returns. If it's not fixed by next week I'm downgrading.

Installing the version of Xcode from the Apple Developer Website only fixes the problem temporarily. The same “Internal error: missingPackageDescriptionModule.” showed up a few hours after installation. I've re-installed Xcode FIVE times. Filed bug with Feedback Assistant (including sysdiagnose files before and after problem occurs): FB9811795.

I tried the workaround and it is insufficient. It works for several hours and then the issue reappears. Reinstalling Xcode again works for a while. I have reinstalled Xcode four times because of this now. I have opened a bug report (FB9811795) and included additional information and TWO sysdiagnose files. The first was created after a clean re-install of Xcode 13.2 from the Apple Developer Website. After less nearly 24 hours the problem resurfaced. The second sysdiagnose file was created right after this. I really hope this helps. Please fix this as quickly as possible.