ci: Synchronize issue labels using a central configuration (#3951)

.github/workflows/README.md

@@ -5,3 +5,5 @@
     Lints the player, and builds and tests each combination of OS and browser.
   - 'update_issues.yaml':
     Updates GitHub issues on a timer.
+  - 'sync-labels.yaml':
+    Synchronize issue labels using a central configuration.

.github/workflows/build_and_test.yaml

@@ -7,7 +7,7 @@ on:
     inputs:
       ref:
         description: "The ref to build and test."
-        required: False
+        required: false
 
 jobs:
   lint:

.github/workflows/sync-labels.yaml

@@ -0,0 +1,32 @@
+# Install this in .github/workflows/ to automate label updates
+name: Sync Labels
+
+on:
+  workflow_dispatch:
+    # Allows for manual triggering.
+    inputs:
+      dry_run:
+        description: "If true, don't make any actual changes"
+        required: false
+        default: false
+  schedule:
+    # Run every week on Sunday at 5:42 AM.
+    - cron: '42 5 * * 0'
+
+jobs:
+  sync-labels:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+        with:
+          repository: joeyparrish/shaka-github-tools
+
+      # TODO: revert to micnncim and new release after landing
+      #       https://github.com/micnncim/action-label-syncer/pull/68
+      - uses: joeyparrish/action-label-syncer@v1.8.0
+        with:
+          dry_run: ${{ github.event.inputs.ref || false }}
+          prune: true
+          manifest: sync-labels/configs/${{ github.repository }}.yaml
+          repository: ${{ github.repository }}