Bump nyc from 13.1.0 to 18.0.0

Bumps [nyc](https://github.com/istanbuljs/nyc) from 13.1.0 to 18.0.0.
- [Release notes](https://github.com/istanbuljs/nyc/releases)
- [Changelog](https://github.com/istanbuljs/nyc/blob/main/CHANGELOG.md)
- [Commits](istanbuljs/nyc@v13.1.0...nyc-v18.0.0)

---
updated-dependencies:
- dependency-name: nyc
  dependency-version: 18.0.0
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

package.json

@@ -13,7 +13,7 @@
     "mocha": "~5.2.0",
     "node-red": "~0.19.5",
     "node-red-node-test-helper": "~0.1.8",
-    "nyc": "^13.1.0"
+    "nyc": "^18.0.0"
   },
   "keywords": [
     "node-red",