Move Muirrum to alumni

[Kobzol]

Move Muirrum to alumni, as they have been inactive on GitHub and Zulip for some time. This is in accordance with https://github.com/rust-lang/leadership-council/blob/main/policies/membership/auto-alumni.md.

Muirrum will be moved to alumni in the following team(s):

• triage (CC @Dylan-DPC)

This pull request should be left open at least for 10 days (until 28.07.2026) to allow the contributor to respond.

CC @Muirrum

If you want to keep being a member of Rust teams, please let us know!

[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/all':
      Deleting member 'Muirrum'
    📝 Editing team 'rust-lang/triage':
      Deleting member 'Muirrum'
    💻 Org membership Diffs:
    ❌ Removing the following members from `rust-lang`:
      - Muirrum

[rustbot]

☔ The latest upstream changes (possibly #2606) made this pull request unmergeable. Please resolve the merge conflicts.