build(deps-dev): bump nyc from 14.1.1 to 15.1.0

Bumps [nyc](https://github.com/istanbuljs/nyc) from 14.1.1 to 15.1.0.
- [Release notes](https://github.com/istanbuljs/nyc/releases)
- [Changelog](https://github.com/istanbuljs/nyc/blob/master/CHANGELOG.md)
- [Commits](istanbuljs/nyc@v14.1.1...v15.1.0)

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

Author: dependabot[bot]

package.json

@@ -42,6 +42,6 @@
     "eslint-config-brightspace": "^0.6.4",
     "jwa": "^1.1.4",
     "mocha": "^6.2.0",
-    "nyc": "^14.1.1"
+    "nyc": "^15.1.0"
   }
 }