build: remove obsolete nyc dep

Author: marionebl

@commitlint/core/package.json

@@ -32,14 +32,6 @@
     ]
   },
   "xo": false,
-  "nyc": {
-    "all": true,
-    "sourceMap": false,
-    "instrument": false,
-    "include": [
-      "source/**/*.js"
-    ]
-  },
   "engines": {
     "node": ">=4"
   },
@@ -76,7 +68,6 @@
     "execa": "0.8.0",
     "globby": "6.1.0",
     "import-from": "2.1.0",
-    "nyc": "10.3.2",
     "path-exists": "3.0.0",
     "resolve-from": "4.0.0",
     "rimraf": "2.6.1",