Merge pull request #20 from softwareforgood/try-to-set-pr-number

Try to set PR_NUMBER

Author: wwahammy

.github/workflows/deploy-to-pantheon.yml

@@ -38,6 +38,7 @@ env:
   SSH_PRIVATE_KEY: ${{ secrets.SSH_PRIVATE_KEY }}
   GITHUB_OWNER: ${{ github.repository_owner }}
   CI_PROJECT_NAME: ${{ github.repository }}
+  PR_NUMBER: ${{github.event.pull_request.number}}
 
 concurrency:
   group: deploy-to-pantheon--${{ github.head_ref || github.ref_name }}