Fix CI installing latest typescript

[nicholas-l]

Currently the latest typescript is installed without a package-lock.json file. This file should be checked in so that the whole dependency tree is deterministic (see: https://nodejs.dev/learn/the-package-lock-json-file). Dont worry as this package-lock will not be used by npm when this package is used as a dependency in other packages.
This PR pins typescript to 4.3.x as typescript 4.4 has a semi-breaking change where they change catch argument from error to unknown (see: https://devblogs.microsoft.com/typescript/announcing-typescript-4-4/#use-unknown-catch-variables).

[nicholas-l]

I have also created another PR so that dependency updates to package.json and package-lock.json are automated by dependabot: #162 now that the dependencies are locked.

[nicholas-l]

I think Test (ubuntu-latest, 13.x) check is never going to complete as it isn't in the test matrix, and it is marked as required. I believe you can remove this required test in the branch protection rules.