Update octocrab for new events and reduced backtraces in errors when they make a release

[0xB10C]

We'd benefit from octocrab merging these and should upgrade when they make a release:

• models: add missing issue event types XAMPPRocky/octocrab#821
• octocrab::Error: don't include unconditional backtrace in Display impl XAMPPRocky/octocrab#824

An alternative would be to use a custom branch with these merged, but I'd prefer to hold off on this for now.

cc @lschuermann