chore: add a label for first pull request

.github/workflows/first-pull-request.yml

@@ -0,0 +1,45 @@
+name: First pull request
+on: pull_request
+
+jobs:
+  welcome:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/github-script@v3
+        with:
+          github-token: ${{secrets.GITHUB_TOKEN}}
+          script: |
+            // Get a list of all issues created by the PR opener
+            // See: https://octokit.github.io/rest.js/#pagination
+            const creator = context.payload.sender.login
+            const opts = github.issues.listForRepo.endpoint.merge({
+              ...context.issue,
+              creator,
+              state: 'all'
+            })
+
+            const issues = await github.paginate(opts)
+
+            for (const issue of issues) {
+              if (issue.number === context.issue.number) {
+                continue
+              }
+
+              if (issue.pull_request) {
+                return // Creator is already a contributor.
+              }
+            }
+
+            await github.issues.addLabels({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              labels: ['first pull request'],
+            });
+
+            await github.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: "Hey ${creator}! Thanks for opening the pull request. If you haven't already, make sure to read our [contribution guidelines](https://github.com/react-navigation/react-navigation/blob/main/CONTRIBUTING.md)."
+            })