specify wheel build target for hatch explicitly

[willh-cmyk]

I'm submitting a fix for building wheels for this package.

I'm getting this error when building wheels for my multistage docker build:

ValueError: Unable to determine which files to ship inside the wheel using the following heuristics: https://hatch.pypa.io/latest/plugins/builder/wheel/#default-file-selection

The most likely cause of this is that there is no directory that matches the name of your project (jupyterhub_kubespawner).

At least one file selection option must be defined in the `tool.hatch.build.targets.wheel` table, see: https://hatch.pypa.io/latest/config/build/

As an example, if you intend to ship a directory named `foo` that resides within a `src` directory located at the root of your project, you can define the following:

[tool.hatch.build.targets.wheel]
packages = ["src/foo"]

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[willh-cmyk]

#831 relevant issue is here

[consideRatio]

Thank you @willh-cmyk! This is a bug I recall running into but never getting down to the details of understanding the fix or what was going on.