Add reddevilmidzy to the rustc-dev-guide team

[reddevilmidzy]

I joined the rustc-dev-guide team thanks to a recommendation from @tshepang.

[github-actions]

Dry-run check results

[WARN  sync_team] sync-team is running in dry mode, no changes will be applied.
[INFO  sync_team] synchronizing crates-io
[INFO  sync_team] synchronizing github
[INFO  sync_team] 💻 Team Diffs:
    📝 Editing team 'rust-lang/rustc-dev-guide':
      Adding member 'reddevilmidzy' with member role
    💻 Repo Diffs:
    📝 Editing repo 'rust-lang/bors':
      Rulesets:
          Ruleset for main
            No changes