Support labeled events

[lumi017]

I would like pr-preview to run only if a specific label is added to a PR. However listening to labeled events, causes pr-preview to skip executing

on:
  workflow_dispatch:
  pull_request:
    branches: [main]
    types:
      - opened
      - reopened
      - synchronize
      - closed
      - labeled

together with

      - name: Create Preview
        if: contains(github.event.pull_request.labels.*.name, 'pr-preview')
        uses: rossjrw/pr-preview-action@v1

Adding a label to the PR results in:

Determining auto action
event_name is pull_request; proceeding
event_type is labeled
unknown event type labeled; no action to take