chore: linter action should run on edits and label adjusts (#13398)

Currently, the linter only runs when the PR is opened. This naturally
means that when the title, description or labels (that it complains
about) is fixed, it does not re-run and confirm that it passes.

Adjust the action so it also runs when the PR labels, title or
descriptions are modified.

.github/workflows/pr-linter.yml

@@ -2,7 +2,15 @@
 # https://github.com/actions/toolkit/blob/master/packages/github/src/context.ts
 
 name: PR Linter
-on: pull_request
+on:
+ pull_request:
+ types:
+ - labeled
+ - unlabeled
+ - edited
+ - opened
+ - synchronize
+ - reopened
 
 jobs:
  validate-pr: