fix: Add QEnum dtype inference

[HCookie]

Description

Add QEnum dtype inference
Closes #61

from qubed.value_types import QEnum

QEnum([0,1]).dtype == "int64"

Contributor Declaration

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• All authors agree to the Contributor License Agreement.
• The code follows the project's coding standards.
• I have performed self-review and added comments where needed.
• I have added or updated tests to verify that my changes are effective and functional.
• I have run all existing tests and confirmed they pass.

🌈🌦️📖🚧 Documentation 🚧📖🌦️🌈
https://sites.ecmwf.int/docs/dev-section/qubed/pull-requests/PR-62

[mathleur]

Looks good to me! @peshence, I think we might be able to change the FDB scanning script to avoid changing some of the types considering this?

[peshence]

Nice