chore(deps-dev): bump @types/node from 15.3.0 to 15.6.1 (#2571)

Bumps [@types/node](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/node) from 15.3.0 to 15.6.1.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/node)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package.json

@@ -69,7 +69,7 @@
     "@types/async": "^3.2.6",
     "@types/cheerio": "^0.22.28",
     "@types/mocha": "^8.2.2",
-    "@types/node": "^15.3.0",
+    "@types/node": "^15.6.1",
     "@types/node-fetch": "^2.5.10",
     "@types/node-notifier": "^8.0.0",
     "@types/nodemailer": "^6.4.1",