Add the pull request labeler Action

https://github.com/actions/labeler
https://github.com/marketplace/actions/labeler

Verified Action

Update labeler.yml

.github/labeler.yml

@@ -0,0 +1,24 @@
+benchmark:
+  - benchmark/**/*
+build:
+  - Makefile
+  - Rakefile
+  - build_config/**/*
+  - lib/**/*
+  - tasks/**/*
+core:
+  - include/**/*
+  - mrblib/**/*
+  - src/**/*
+  - test/**/*
+doc:
+  - CONTRIBUTING.md
+  - README.md
+  - doc/**/*
+  - examples/**/*
+github:
+  - .github/**/*
+mrbgems:
+  - mrbgems/**/*
+oss-fuzz:
+  - oss-fuzz/**/*

.github/workflows/labeler.yml

@@ -0,0 +1,14 @@
+name: Pull Request Labeler
+on:
+  - pull_request_target
+jobs:
+  triage:
+    permissions:
+      contents: read
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/labeler@v4
+        with:
+          repo-token: "${{ secrets.GITHUB_TOKEN }}"
+          sync-labels: true