build: avoid duplicated CI runs

[caarlos0]

running on both push and pull_request end up running the same job twice for a push on a PR, which waste our CI minutes.

[codecov]

Codecov Report

Attention: 3823 lines in your changes are missing coverage. Please review.

Comparison is base (050a0d1) 50.52% compared to head (aeb33df) 47.77%.
Report is 94 commits behind head on main.

❗ Current head aeb33df differs from pull request most recent head 6264003. Consider uploading reports for the commit 6264003 to get more accurate results

Files	Patch %	Lines
pkg/web/git_lfs.go	25.15%	574 Missing and 27 partials ⚠️
pkg/git/lfs.go	1.98%	297 Missing ⚠️
pkg/ui/pages/repo/stash.go	0.00%	185 Missing ⚠️
pkg/backend/webhooks.go	17.82%	162 Missing and 4 partials ⚠️
pkg/ssh/cmd/webhooks.go	45.90%	156 Missing and 9 partials ⚠️
pkg/ui/pages/repo/files.go	5.00%	152 Missing ⚠️
pkg/lfs/http_client.go	5.92%	127 Missing ⚠️
pkg/ui/pages/repo/refsitem.go	5.38%	123 Missing ⚠️
pkg/backend/repo.go	40.59%	93 Missing and 27 partials ⚠️
pkg/store/database/lfs.go	22.05%	105 Missing and 1 partial ⚠️
... and 82 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #433      +/-   ##
==========================================
- Coverage   50.52%   47.77%   -2.76%     
==========================================
  Files         107      154      +47     
  Lines        8209    13068    +4859     
==========================================
+ Hits         4148     6243    +2095     
- Misses       3767     6337    +2570     
- Partials      294      488     +194     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.