Remove deprecated total_count option from paginated List struct

[belyakov-am]

Is your feature request related to a problem? Please describe.

Currently List for pagination response has total_count field which is not supported by Stripe API for a while.
When I saw this field, I assumed it's populated by the API (despite being Option) and found out that it's outdated only during testing.

https://github.com/arlyon/async-stripe/blob/master/src/params.rs#L284-L293

Describe the solution you'd like

Ideal solution would be to just remove it

Describe alternatives you've considered

Another okayish way is to at least put a comment mentioning that this field shouldn't be used

Additional context

No response