fix: Use list pull request files api

[levsa]

and sum the changes for each file instead of parsing diff to solve the issue with max 300 files error from rest api.

Probably also solves #53 ?

[yahel2410]

Hey, what's the status here? can it be merged?

[pascalgn]

Fixes #53

[pascalgn]

Thanks for the PR, it's merged now! 👍