Update readme to not mention threading

[JonatanMartens]

No description provided.

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[coveralls]

Pull Request Test Coverage Report for Build 2176368648

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 94.231%

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Totals
Change from base Build 2086020650:	0.0%
Covered Lines:	735
Relevant Lines:	780

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💛 - Coveralls