Update stats file

[wfordh]

Wanted to get this up here even though it's not 100% ready yet. Addresses issue #18. Using my add_type_hints branch from PR #19 instead of main since it works off of that.

I added a logger warning since the Stats API is not technically documented / supported on Sleeper anymore. I also reworked a bunch of the methods and added some attributes to the class so that the stats that are pulled are stored directly in it and not an external object like before. That seems like better OOP to me, but I might be wrong. Added KeyError to the try / except clauses to not make them overly broad.

Some open questions I still have include

• Should we pull any of the stats on init? Right now data is pulled on init for the User and League classes, but not Players. Maybe that's due to the size of the data that comes in for players and stats? Right now I think I'd lean don't pull the stats.
• Should the stats have a season attached to them? Just in case someone is pulling across seasons
• Should the full and weekly stats be public? Right now they're private attributes as they have the _ prefix

[wfordh]

I opted for changing as little as possible for now to not introduce any sort of breaking changes for users before the season. Streamlined some by replacing try / except clauses with the Python dictionary's built-in get() method. Otherwise just adding the warning and docstrings for each method.

[wfordh]

Gonna go ahead and merge - looks like I can do that without an approval since the base branch isn't master / main. Will make a PR then for merging into main and will need an approval there