chore: Improve increment version script (#1339)

## Summary

- Using an independent value for the build-number and auto-increment
using `agvtool next-version`

Github action output example:

<img width="287" alt="Screenshot 2023-08-30 at 11 33 54"
src="https://github.com/Adyen/adyen-ios/assets/4838877/91a6540c-7b49-4a7b-96ae-5a7890552b64">