Bump typescript from 3.9.7 to 4.0.2

Bumps [typescript](https://github.com/Microsoft/TypeScript) from 3.9.7 to 4.0.2.
- [Release notes](https://github.com/Microsoft/TypeScript/releases)
- [Commits](https://github.com/Microsoft/TypeScript/compare/v3.9.7...v4.0.2)

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

package.json

@@ -48,7 +48,7 @@
         "terser-webpack-plugin": "^4.1.0",
         "tfx-cli": "^0.8.1",
         "ts-loader": "^8.0.2",
-        "typescript": "^3.9.7",
+        "typescript": "^4.0.2",
         "webpack": "^4.44.1",
         "webpack-cli": "^3.3.12"
     }