www/firefox: update to 108.0.2 (rc1)

Release Notes (soon):

https://www.mozilla.org/en-US/firefox/108.0.2/releasenotes/

While here, set harfbuzz dependency straight after 2022Q4 finally
went away.

(cherry picked from commit 662f809343ab4b176cb9f96eec7ea9061a718331)