crostestutils: Remove dgoyette from OWNERS

dgoyette's last day at Google was 2020-09-30. This CL cleans up his
username from the crostestutils project.

BUG=b:169854527
TEST=None

Change-Id: I4ac6b4a5925903de801524e24ddcc2478e8a6e11
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crostestutils/+/2443309
Tested-by: Greg Edelston <gredelston@google.com>
Reviewed-by: Andrew Luo <aluo@chromium.org>
Commit-Queue: Greg Edelston <gredelston@google.com>