Add theemathas to T-release

[Mark-Simulacrum]

@theemathas has been helping for the last few release cycles with Crater triage, adding them to the team to recognize that work. Thanks!

Largely replaces #2449 (I still think that would make some sense but it removes immediate need/concern for it).

[github-actions]

Dry-run check results

[WARN  rust_team::sync] sync-team is running in dry mode, no changes will be applied.
[INFO  rust_team::sync] synchronizing crates-io
[INFO  rust_team::sync] synchronizing github
[INFO  rust_team::sync] 💻 Team Diffs:
    📝 Editing team 'rust-lang/release':
      Adding member 'theemathas' with member role