[Autoroller] Fix github label typo
[Autoroller] Fix github label typo

This stuck around for way too long..

Bug: skia:9146
Change-Id: I40d7c6be6ba0291b38a67fb89fbf2b62e9a2eee4
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/218545
Reviewed-by: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@google.com>
Commit-Queue: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot