Fix GameData absChallenges model

[gitknr]

Fix GameData absChallenges validation

## Summary

Fixes `GameData.absChallenges` parsing for MLB API responses where `absChallenges` is returned as an object containing ABS-specific challenge fields.

## Why

Some game feed responses return `gameData.absChallenges` as:

- a single object, not a list
- nested team challenge info using `usedSuccessful`, `usedFailed`, and `remaining`

This caused Pydantic validation errors when calling `get_game()` for affected games.

## What

- Added ABS-specific models for `absChallenges`
- Updated `GameData.abs_challenges` to use the new ABS challenge model
- Updated the `GameData` docstring to reflect the correct field type

## Tests

Verified that `mlb.get_game(822974)` now parses successfully and exposes ABS challenge data through:

- `game.game_data.abs_challenges.away.used_successful`
- `game.game_data.abs_challenges.away.used_failed`
- `game.game_data.abs_challenges.away.remaining`

existing tests were all executed & pass.

Note: I checked `development`, but `Mlb.get_game()` does not exist on that branch. This validation issue occurs in the current `main` implementation of `get_game()`, so this PR targets `main`.

### Risk and impact

Risk level: Minimal

This change is limited to the `GameData.absChallenges` model parsing. It adds a more accurate model for the ABS challenge payload returned by the MLB API and updates `GameData.abs_challenges` to use that model instead of a generic list/dict shape.

The main risk is that if the MLB API returns another unexpected `absChallenges` shape, parsing could still fail for affected games. If something goes wrong, impact should be limited to `get_game()` responses that include `gameData.absChallenges`; unrelated endpoints and non-ABS game data should be unaffected.