chore(package): update nyc to version 15.0.1

Closes #39

Author: greenkeeper[bot]

package.json

@@ -63,7 +63,7 @@
     "eslint-plugin-jsx-a11y": "^6.2.3",
     "eslint-plugin-react": "^7.14.3",
     "mocha": "^6.1.4",
-    "nyc": "^14.1.1",
+    "nyc": "^15.0.1",
     "pg": "^7.12.1",
     "pg-hstore": "^2.3.3",
     "pgpass": "^1.0.2",