auto merge all contributors bot (#1010)

.github/workflows/label-all-contributors.yml

@@ -0,0 +1,20 @@
+name: Auto-merge All-Contributors bot
+
+on: pull_request
+
+jobs:
+  apply-label:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/github-script@0.9.0
+        with:
+          github-token: ${{secrets.GITHUB_TOKEN}}
+          script: |
+            if (context.payload.pull_request.user.login === 'allcontributors[bot]') {
+              github.issues.addLabels({
+                issue_number: context.payload.pull_request.number,
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                labels: ['squash when passing']
+              })  
+            }