Fix polygon get historical prices

[brettelliot]

Description by Korbit AI

What change is being made?

Refactor and enhance functionality for calculating and handling historical prices, managing various data source configurations, and ensuring proper order of execution during drift rebalancing.

Why are these changes being made?

The changes address issues with covered short positions, improve handling of historical prices and trading day calculations, and optimize test coverage. This refactor allows for better flexibility and accuracy in data handling, especially over long weekends, and ensures proper validations and usage of API keys with more robust configuration management.

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[korbit-ai]

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[brettelliot]

Updated summary of these changes

DriftRebalancer:

• removed an uneeded warngin
• fixed a bug in the logic so that now it correctly covers shorts when rebalancing.

AlpacaData / Pandas Data

• now both use the same logic for getting extra days in order to provide the right number of bars. Before I was multiplying the length by 1.5. Now im doing what @bigredengineer. said to do which is calculate the number of weeks and add a small padding for 3 day weekends.

yahoodata:

• fixed a simple bug where timeshift was not always a timedelta object.

test_example_strategies / test_polygon

• added checks to skip certain tests without paid polygon subscriptions

test_gest_historical_prices

• most of my time was spent here. i made specific tests to check a variety of things. these tests helped prove certain things were working.