GH first-interaction action is busted, workaround

This works around a busted actions/first-interaction@v1 until it's fixed
actions/first-interaction#101

Even after it's fixed it's probably good to keep around just so it won't
block merges in the future.

Signed-off-by: Michael Peters <mpeters@redhat.com>

.github/workflows/greetings.yml

@@ -7,6 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/first-interaction@v1
+      continue-on-error: true
       with:
         repo-token: ${{ secrets.GITHUB_TOKEN }}
         issue-message: 'Thank you for reporting your first issue. If the issue relates to a change you intend to work on, please ask that someone assign it to you.'