support Base.eltype for QuantumObject

[ytdHuang]

This helps to directly obtain the element type in QuantumObject.data, e.g., Int64, Float64, ComplexF64 ...
I think this would be quite useful when developing new functionality in the future.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 90.19%. Comparing base (be2142d) to head (8f4926c).
Report is 3 commits behind head on main.

Files	Patch %	Lines
src/quantum_object.jl	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #29      +/-   ##
==========================================
- Coverage   90.23%   90.19%   -0.05%     
==========================================
  Files          16       16              
  Lines        1567     1570       +3     
==========================================
+ Hits         1414     1416       +2     
- Misses        153      154       +1     

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[ytdHuang]

I'm didn't write a test for this feature since it's just calling the function in Base.
For the code coverage, it will be automatically covered by the tests for new developed features.

[albertomercurio]

Yes this is fine. Thank you.

BTW, I'm at RIKEN right now 😄

[ytdHuang]

Yes this is fine. Thank you.

BTW, I'm at RIKEN right now 😄

Nice~ I'll arrive at Sunday afternoon this week.