Add workflow for labeling new PRs as needs-triage (#10690)

Author: aeschright

.github/workflows/issues.yml

@@ -5,7 +5,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v1.0.0
-    - name: Apply Triage Label
+    - name: Apply Issue Triage Label
       uses: actions/github@v1.0.0
       if: github.event.action == 'opened'
       env:

.github/workflows/pull_requests.yml

@@ -0,0 +1,15 @@
+name: PR triage
+on:
+  pull_request:
+    types: [opened]
+jobs:
+  markPRsForTriage:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v1.0.0
+    - name: Apply PR Triage Label
+      uses: actions/github@v1.0.0
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      with:
+        args: label needs-triage