Add a file for testing revert (flutter#3065)

File to add for revert testing. The revert will work but for some reason double events are getting processed for the same revert PR. This doesn't cause any issues just throws an error that can be ignored but I would rather fix the issue.

*List which issues are fixed by this PR. You must list at least one issue.*

*If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].*

auto_submit/testfile.txt

@@ -0,0 +1 @@
+revert this change.