Revert "fix(gha): run CI on PR synchronize"

This reverts commit 51c7ef1.

Author: bkrem

.github/workflows/ci.yml

@@ -8,7 +8,6 @@ jobs:
   ci:
     name: CI
     runs-on: ubuntu-latest
-    if: github.event.action == 'opened' || github.event.action == 'synchronize'
     strategy:
       fail-fast: false # don't abort all jobs in matrix if one fails
       matrix: