chore(ci): update CI to run on pull_request event

[rwaskiewicz]

Pull request checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• Build (npm run build) was run locally and any changes were pushed

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe): Backport of fix(testing): puppeteer v10 support #2934

What is the current behavior?

Currently, GitHub Actions don't trigger for PRs created from forked repos, only when a push is made directly to the Stencil repo

What is the new behavior?

update CI to run on pull_request event to run on PRs from forked repos

Does this introduce a breaking change?

• Yes
• No

Other information

• GitHub Actions Documentation for PRs from Forked Repos
• GitHub Actions Documentation for push events

Runs your workflow when someone pushes to a repository branch, which triggers the push event.
(not particularly helpful on its own admittedly)

• I used this configuration from the Capacitor team as the source of inspiration/start of my documentation reading

[ltm]

Specifying the branches is not necessary in this case:

Suggested change

	on:
	push:
	branches:
	- '**'
	pull_request:
	branches:
	- '**'
	on:
	push:
	pull_request:

Alternatively you can use the shorthand on: [push, pull_request].

[rwaskiewicz]

I went with the shorthand, that 'felt more readable' to me

[rwaskiewicz]

Hmmm but it looks like as-is (I didn't think to check beforehand) these events aren't exclusive. IE right now, there's a pull_request and push set of checks running. Let me see what we can do about that

[rwaskiewicz]

@ltm I updated this to be explicit to run CI on our protected branches, and once on CI. I think that achieves what we effectively want - a clean CI run on the master (and v3.0.0-dev) branches every time we merge to them, but doesn't run both the ubuntu & windows builds 2x each on a PR. At this point, I think I prefer being "explicit" about branches in the pull_request event, even if it just is a glob. Let me know what you think.