[swarming] fix test_seq.py import error
[swarming] fix test_seq.py import error

It wasn't correct import name.

Bug: 1869090
Change-Id: I12d5c2f0b71c4b46e11b9592f88faac4fefca0fc
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/1871278
Commit-Queue: Junji Watanabe <aaef61ef98ffea505db831f310be2a0eb8492537@google.com>
Commit-Queue: Takuto Ikuta <71927f930fca81015e0f496c65cd126ab1a692e3@chromium.org>
Auto-Submit: Junji Watanabe <aaef61ef98ffea505db831f310be2a0eb8492537@google.com>
Reviewed-by: Takuto Ikuta <71927f930fca81015e0f496c65cd126ab1a692e3@chromium.org>

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