build(deps-dev): bump @types/node from 14.17.2 to 15.9.0

Bumps [@types/node](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/node) from 14.17.2 to 15.9.0.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/node)

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

package.json

@@ -24,7 +24,7 @@
   "devDependencies": {
     "@types/chai": "^4.2.0",
     "@types/mocha": "^8.0.0",
-    "@types/node": "^14.0.1",
+    "@types/node": "^15.9.0",
     "chai": "^4.1.2",
     "coveralls": "^3.0.7",
     "mocha": "^7.0.1",