Add coverage report

Author: casmith

package.json

@@ -4,7 +4,7 @@
   "description": "Calender Versioning (calver) plugin for Release It!",
   "main": "index.js",
   "scripts": {
-    "test": "mocha **/*-tests.js",
+    "test": "nyc --reporter=lcovonly mocha **/*-tests.js --timeout 10000",
     "release": "release-it -- --ci"
   },
   "repository": {
@@ -35,6 +35,7 @@
     "mocha": "^8.2.1"
   },
   "devDependencies": {
+    "nyc": "^15.1.0",
     "release-it": "^14.6.2"
   },
   "peerDependencies": {