chore: remove workaround for "Excessive Stack Depth" from TS3.2

[imnotjames]

Description of change

this was added to our typing to work around issue described in
microsoft/TypeScript#21592 - however, as of TS 3.6.3 it has not been
an issue

fixes #7338

Pull-Request Checklist

• Code is up-to-date with the master branch
• npm run lint passes with this change
• npm run test passes with this change
• This pull request links relevant issues as Fixes #0000
• There are new or updated unit tests validating the change
• Documentation has been updated to reflect this change
• The new commits follow conventions explained in CONTRIBUTING.md