Update review-trigger.yml (#4137)

Followup after https://github.com/paritytech/polkadot-sdk/pull/3431
Per
https://stackoverflow.com/questions/63188674/github-actions-detect-author-association
and https://michaelheap.com/github-actions-check-permission/
looks like just checking NOT a MEMBER is not correct, Not a CONTRIBUTORs
check should be included

.github/workflows/review-trigger.yml

@@ -35,6 +35,7 @@ jobs:
           github.event_name == 'pull_request_target' &&
           github.event.action == 'synchronize' && 
           github.event.sender.login == github.event.pull_request.user.login && 
+          github.event.pull_request.author_association != 'CONTRIBUTOR' && 
           github.event.pull_request.author_association != 'MEMBER'
         run: |
           echo "User's association is ${{ github.event.pull_request.author_association }}"