Add tommasin to //components/privacy_sandbox/owners

Change-Id: I2b824633bd061cfa825bf7ff99dbb04dea61b6ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5604766


Reviewed-by: Abe Boujane <boujane@google.com>
Reviewed-by: Kevin Graney <kmg@google.com>
Commit-Queue: Nicola Tommasi <tommasin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1312626}