Bump typescript from 2.9.2 to 3.9.2

Bumps [typescript](https://github.com/Microsoft/TypeScript) from 2.9.2 to 3.9.2.
- [Release notes](https://github.com/Microsoft/TypeScript/releases)
- [Commits](microsoft/TypeScript@v2.9.2...v3.9.2)

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

package.json

@@ -91,7 +91,7 @@
     "nyc": "^15.0.0",
     "pre-commit": "^1.1.1",
     "require-globify": "^1.3.0",
-    "typescript": "^2.8.3",
+    "typescript": "^3.9.2",
     "uglify-js": "^3.6.9",
     "watch": "^1.0.0"
   },