Bump nyc from 14.1.1 to 15.0.0

Bumps [nyc](https://github.com/istanbuljs/nyc) from 14.1.1 to 15.0.0.
- [Release notes](https://github.com/istanbuljs/nyc/releases)
- [Changelog](https://github.com/istanbuljs/nyc/blob/master/CHANGELOG.md)
- [Commits](https://github.com/istanbuljs/nyc/compare/v14.1.1...v15.0.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -46,7 +46,7 @@
     "json-schema-to-markdown-table": "^0.4.0",
     "mocha": "6.2.2",
     "mocha-junit-reporter": "^1.9.1",
-    "nyc": "^14.1.1",
+    "nyc": "^15.0.0",
     "prettier": "^1.19.1",
     "ts-node": "^8.4.1",
     "typescript": "^3.6.4",