Fix crypto loading for Binance

[alexferrari88]

Description

In #1794, it is reported that trying to load cryptos with Binance using small caps letters (e.g. btc vs BTC) for the crypto name, generates an error. This is due to Binance not accepting small caps letters for crypto names. This PR fixes that.

How has this been tested?

$> crypto
`$ crypto> load -c btc --source bin

Checklist:

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• Update our tests following these guidelines.
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Others

• I have performed a self-review of my own code.
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• New and existing unit tests pass locally with my changes. You can test this locally using pytest tests/....

[jmaslek]

Damn. Bug fix in record time 🚀🚀🚀

[alexferrari88]

Damn. Bug fix in record time 🚀🚀🚀

In all fairness, this was a super easy one 😄