Add PR labeler to Github action (#826)

.github/labeler.yml

+---
+A-ci:
+  - any: ['.github/**/*']
+
+A-contracts:
+  - any: ['packages/contracts/**/*']
+
+A-geth:
+  - any: ['l2geth/**/*']
+
+A-integration-tests:
+  - any: ['integration-tests/**/*']
+
+A-ts-packages:
+  - any: ['packages/**/*']
+    all: ['!packages/contracts/**/*']
+
+M-batch-submitter:
+  - any: ['packages/batch-submitter/**/*']
+
+M-contracts:
+  - any: ['packages/contracts/**/*']
+
+M-core-utils:
+  - any: ['packages/core-utils/**/*']
+
+M-dtl:
+  - any: ['packages/data-transport-layer/**/*']
+
+M-hardhat-ovm:
+  - any: ['packages/hardhat-ovm/**/*']
+
+M-ops:
+  - any: ['ops/**/*']
+
+M-smock:
+  - any: ['packages/smock/**/*']

.github/workflows/labeler.yml

+---
+name: "Pull Request Labeler"
+on:
+  - pull_request_target
+
+jobs:
+  pr-labeler:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/labeler@main
+        with:
+          repo-token: "${{ secrets.GITHUB_TOKEN }}"
+          configuration-path: .github/labeler.yml