rename the parameter name of from_json_dict() to match python

[arvidn]

This allows calling from_json_dict() with a named argument, like: from_json_dict(json_dict=obj).

For example: https://github.com/Chia-Network/chia-blockchain/blob/main/tests/wallet/rpc/test_wallet_rpc.py#L1529

[coveralls-official]

Pull Request Test Coverage Report for Build 6992171724

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.001%) to 85.827%

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Totals
Change from base Build 6984633742:	0.001%
Covered Lines:	9986
Relevant Lines:	11635

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💛 - Coveralls