chore: Update dependencies, and migrate code to 2021 edition

[Uzaaft]

The title pretty much says it all. Just some maintenance for this crate.

[coveralls]

Pull Request Test Coverage Report for Build 2985218226

• 2 of 6 (33.33%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.4%) to 83.544%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/lib.rs	2	6	33.33%
<!--	Total:	2	6	33.33%	-->

Totals
Change from base Build 1802547170:	-0.4%
Covered Lines:	331
Relevant Lines:	348

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💛 - Coveralls

[danielhstahl]

Looks like its still 2018?

[Uzaaft]

Ops, had to revert it for a moment. Give me 2s and I'll fix that

[Uzaaft]

My bad. Should be 2021 now

[Uzaaft]

2 tests seems to fail due to some floating point stuff. Screen below. Perhaps I could go ahead and reduce the number of decimals we use in the test if it's alright with you danielhstahl

List over tests:

[danielhstahl]

Test seem to be passing in GHA?

[Uzaaft]

peculiar....very peculiar