fix exchange betfair links

[patrickacioli]

For some reason, some exchange links were set to sb_inplay.

[meoww-bot]

As I see, it's still use ex/inplay as endpoint, you can check the docs from here, or if you can give me some reference docs？

[patrickacioli]

The endpoint for some methods is set to self._sb_inplay, but hasn't.

ex_inplay

Is https://api.betsapi.com/v1/betfair/ex/inplay (self._ex_inplay), not (self._sb_inplay).

_ex_upcoming

Is self._ex_upcoming = https://api.betsapi.com/v1/betfair/ex/upcoming (self._ex_upcoming), not (self._sb_inplay).

ex_event

Is self._ex_event = https://api.betsapi.com/v1/betfair/ex/event (self._ex_upcoming), not (self._sb_inplay).

I think it's just a typo.