Add series_status to schedule

[WardBrian]

This exposes the seriesStatus(result) field to the schedule() function. This is mainly useful during the postseason, but exists year-round.

Example:

>>> import statsapi
>>> # game which has finished
>>> print(statsapi.schedule()[0]['series_status'])
HOU leads 2-0
>>> # game which is scheduled
>>> print(statsapi.schedule('2022-10-14')[1]['series_status']) 
Series tied 1-1

[toddrob99]

Thank you. Will include in next release.