Clang upload script: branch from origin/main instead of origin/master

The chromium "master" branch was recently renamed to "main".

Change-Id: I8b5c890fc90e35f00b353592f8214cb91ac2be45
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2822162
Auto-Submit: Arthur Eubanks <aeubanks@google.com>
Reviewed-by: Hans Wennborg <hans@chromium.org>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#872080}
GitOrigin-RevId: a12157b5f3148e5281f40437f688b8b07177e91a
1 file changed