[swarming] fix typo in comment
[swarming] fix typo in comment

Change-Id: I73238768132b2ec33825db1461af72f2efb4ec14
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/2226252
Commit-Queue: Junji Watanabe <aaef61ef98ffea505db831f310be2a0eb8492537@google.com>
Commit-Queue: Ye Kuang <1cd89f22f3967fc3dcb883b53940be4b98ec483f@google.com>
Auto-Submit: Junji Watanabe <aaef61ef98ffea505db831f310be2a0eb8492537@google.com>
Reviewed-by: Ye Kuang <1cd89f22f3967fc3dcb883b53940be4b98ec483f@google.com>

luci/luci-py,luci/luci-py,luci/luci-py,luci/luci-py