ci: use lcovonly reporter for the test-ci script (#584)

Co-authored-by: Jon Church <[email protected]>

package.json

@@ -44,7 +44,8 @@
   "scripts": {
     "lint": "eslint .",
     "test": "mocha --reporter spec --check-leaks test/",
-    "test-ci": "nyc --reporter=lcov --reporter=text npm test",
+    "test-ci": "nyc --reporter=lcovonly --reporter=text npm test",
+
     "test-cov": "nyc --reporter=html --reporter=text npm test"
   }
 }