Add TypeScript 3.7 support

[nwtgck]

Hi developers,

Thank you very much for the wonderful project! Currently, CodeFactor doesn't seem to support TypeScript 3.7 features such as Optional chaining and Nullish coalescing.

Here are CodeFactor's issues related to the features.
https://www.codefactor.io/repository/github/nwtgck/piping-server/commit/5617fe76ebec4ac9337ca8690156ce7bfa359fa2

Here is a PR auto-generated by CodeFactor.
https://github.com/nwtgck/piping-server/pull/221/files
The code change is not proper syntax in TypeScript 3.7.

Example: Optional chaining

Example: Nullish coalescing

[cordis-dev]

@nwtgck thanks for reporting, TypeScript is now updated to 3.7.2.