Bump typescript from 3.8.3 to 4.1.2

Bumps [typescript](https://github.com/Microsoft/TypeScript) from 3.8.3 to 4.1.2.
- [Release notes](https://github.com/Microsoft/TypeScript/releases)
- [Commits](microsoft/TypeScript@v3.8.3...v4.1.2)

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

package.json

@@ -49,7 +49,7 @@
     "rollup": "^2.18.1",
     "tap-dot-b": "^1.0.1",
     "tslib": "^2.0.0",
-    "typescript": "^3.8.3",
+    "typescript": "^4.1.2",
     "watch": "^1.0.2"
   },
   "files": [