Overload Base.UInt8 explicitly

[felixcremer]

This would hopefully get rid of the following warning in julia 1.12

 ┌ Zarr
│  WARNING: Constructor for type "UInt8" was extended in `Zarr` without explicit qualification or import.
│    NOTE: Assumed "UInt8" refers to `Base.UInt8`. This behavior is deprecated and may differ in future versions.`
│    NOTE: This behavior may have differed in Julia versions prior to 1.12.
│    Hint: If you intended to create a new generic function of the same name, use `function UInt8 end`.
│    Hint: To silence the warning, qualify `UInt8` as `Base.UInt8` in the method signature or explicitly `import Base: UInt8`.
└  

[mkitti]

I slipped a commit like this into #182 , but yes, doing this independently is best.

[coveralls]

Pull Request Test Coverage Report for Build 14908265411

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-1.2%) to 84.868%

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Totals
Change from base Build 13680422725:	-1.2%
Covered Lines:	903
Relevant Lines:	1064

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💛 - Coveralls

[mkitti]

Looks good to me.