ci: add PR labeler

[mpoke]

Description

Closes: NA

---

Author Checklist

All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.

I have...

• Included the correct type prefix in the PR title
• Targeted the correct branch (see PR Targeting)
• Provided a link to the relevant issue or specification
• Reviewed "Files changed" and left comments if necessary
• Confirmed all CI checks have passed

Reviewers Checklist

All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.

I have...

• Confirmed the correct type prefix in the PR title
• Confirmed all author checklist items have been addressed
• Confirmed that this PR does not change production code

[insumity]

Is the C:Testing the label applied when change under app/**/*, cmd/**/* etc. If yes, why introduce this label for changes under app and cmd? Also, would it be possible to add this label if modification in a _test file.

[mpoke]

Both app/* and cmd/* are only used for testing. Every chain will have its own. Maybe we can have a better split, maybe with a better label. I'll let @p-offtermatt and @MSalopek to suggest something.

All PRs that change the production code should also change the _test files as they will have unit tests. I'm not sure how valuable is to add a special label for that.

[p-offtermatt]

I don't think I have an opinion on that yet, I would suggest we see how these labels feel and we can adjust later.

[insumity]

LGTM

[shaspitz]

Seems we could also just look at what files are changed for a PR and determine these mental notes ourselves, but overall not opposed to these tags. LGTM