Add github action workflow to produce coverage

.github/workflows/coveralls.yml

@@ -0,0 +1,16 @@
+name: "Coveralls"
+on: [push, pull_request]
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - uses: actions/setup-node@v3
+      with:
+        node-version: 18
+    - run: npm ci
+    - run: npm run coverage
+    - uses: coverallsapp/github-action@master
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}

package.json

@@ -32,9 +32,10 @@
     ],
     "scripts": {
         "build": "tsc --build tsconfig.dist.json",
+        "coverage": "jest --coverage",
         "clean": "rm -rf index.{js,js.map,d.ts} ./lib/*.{js,js.map,d.ts} ./tests/*.{js,js.map,d.ts}",
-        "test": "jest",
-        "prepublishOnly": "npm run build"
+        "prepublishOnly": "npm run build",
+        "test": "jest"
     },
     "dependencies": {},
     "devDependencies": {