Upgrade nyc dev dependency

Author: Sascha Goldhofer

package.json

@@ -32,7 +32,7 @@
     "chai": "^4.2.0",
     "eslint": "^7.12.0",
     "mocha": "^8.2.0",
-    "nyc": "^14.1.1",
+    "nyc": "^15.1.0",
     "terser-webpack-plugin": "^5.0.1",
     "typescript": "^4.0.3",
     "watch": "^1.0.1",