Remove dpranke@chromium.org from OWNERS.

I've consistently switched over to using dpranke@google.com for all
my work and should no longer have the @chromium.org address listed
in OWNERS.

Change-Id: Ibafa6d0fe0c0673a3216ade62b5997af62b06e76
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2335909
Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@google.com>

OWNERS

@@ -1,7 +1,6 @@
 set noparent
 
 apolito@google.com
-dpranke@chromium.org
 dpranke@google.com
 ehmaldonado@chromium.org
 ehmaldonado@google.com