build: add coveralls action

.github/workflows/coveralls.yml

@@ -0,0 +1,26 @@
+name: Build
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  coveralls:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "20"
+      - name: Install dependencies
+        run: npm install --no-optional
+      - name: Generate coverage
+        run: npm run coverage-lcov
+      - name: Coveralls
+        uses: coverallsapp/github-action@v2.3.0
+        with:
+          github-token: ${{ github.token }}
+          file: ./coverage/lcov.info

package.json

@@ -26,6 +26,7 @@
   "license": "MIT",
   "scripts": {
     "coverage": "c8 npm test",
+    "coverage-lcov": "c8 npm test && c8 report --reporter=lcovonly",
     "coveralls": "c8 npm test && c8 report --reporter=text-lcov | coveralls",
     "lint": "eslint -c config/eslint.config.js src/**.*js",
     "pretest": "npm run lint",