run CI on all PR branches

[andrewkolos]

This is a follow-up to #280 (comment). In summary, we only run CI checks on PRs against the main branch. However, in cases where an older major version of a package needs to be patched, it doesn't make sense to PR against main. CI won't run for these PRs, but it probably should.

This updates our GitHub CI configs to run checks against PRs against any branch.

---

• I’ve reviewed the contributor guide and applied the relevant portions to this PR.

Contribution guidelines:

• See our contributor guide for general expectations for PRs.
• Larger or significant changes should be discussed in an issue before creating a PR.
• Contributions to our repos should follow the Dart style guide and use dart format.
• Most changes should add an entry to the changelog and may need to rev the pubspec package version.
• Changes to packages require corresponding tests.

Note that many Dart repos have a weekly cadence for reviewing PRs - please allow for some latency before initial review feedback.

[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:unified_analytics	6.1.2	ready to publish	unified_analytics-v6.1.2
package:cli_config	0.2.0	already published at pub.dev
package:extension_discovery	2.0.1-wip	WIP (no publish necessary)
package:graphs	2.3.2-wip	WIP (no publish necessary)

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.

[devoncarew]

Thanks for the update! lgtm modulo the change to the publishing workflow file.

[andrewkolos]

FYI: I've created a release for unified_analytics-v6.1.2 since it looks like that never got made after #277 merged. I did this as I didn't want this PR merging to trigger a release from CI.

[christopherfujino]

LGTM