Give trigger.py executable bit.
Give trigger.py executable bit.

Bug: angleproject:3162
Change-Id: I4ebd0ccf397568aeaa62a033155e70024a806965
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2420333
Commit-Queue: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>
Reviewed-by: Jonah Ryan-Davis <682bdb9e7d8ba359ef169b8db374e7a99d394a46@google.com>

ppy/angle,ppy/angle,ppy/angle,ppy/angle