chore: Fix CI to run on public forks

[austinvalle]

Related Issue

N/A

Description

The push event does not run for public forks, so we should switch to using the pull_request target so that we get the "requires approval" dialogue: https://docs.github.com/en/actions/reference/workflows-and-actions/events-that-trigger-workflows#pull-request-events-for-forked-repositories

Rollback Plan

• If a change needs to be reverted, we will roll out an update to the code within 7 days.

Changes to Security Controls

No

[rainkwan]

Exciting