Enable regression labeling aliases

[apiraino]

Enabling label aliases when regressions bleed into the next release channel (nightly -> beta, beta -> stable).

This configuration enables these two aliases:

• @rustbot label to-beta (switch regression label -> beta)
• @rustbot label to-stable (switch regression label -> beta)

Pending merge of triagebot#2172

[rustbot]

triagebot.toml has been modified, there may have been changes to the review queue.

cc @davidtwco, @wesleywiser

[rustbot]

r? @Mark-Simulacrum

rustbot has assigned @Mark-Simulacrum.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[apiraino]

r? @Urgau since you kindly reviewed triagebot#2172

[rustbot]

Error: Invalid triagebot.toml at position 41:10:

TOML parse error at line 41, column 10
   |
41 | [relabel.to-stable]
   |          ^^^^^^^^^
unknown field `to-stable`, expected `allow-unauthenticated`

Please file an issue on GitHub at triagebot if there's a problem with this bot, or reach out on #triagebot on Zulip.