Bump @types/node from 12.20.13 to 15.6.0

Bumps [@types/node](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/node) from 12.20.13 to 15.6.0.
- [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

@@ -39,7 +39,7 @@
   "devDependencies": {
     "@types/chai": "^4.2.3",
     "@types/mocha": "^7.0.2",
-    "@types/node": "^12.7.5",
+    "@types/node": "^15.6.0",
     "@types/uuid": "^7.0.0",
     "@typescript-eslint/eslint-plugin": "^2.3.0",
     "@typescript-eslint/parser": "^2.3.0",