Add strict typing to radio_browser

[cdce8p]

Proposed change

The integration is already fully typed.

Both dependency is typed as well.
https://github.com/frenck/python-radios/blob/v0.3.1/src/radios/py.typed
https://github.com/pycountry/pycountry/blob/23.12.11/src/pycountry/py.typed

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• Dependency upgrade
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• Breaking change (fix/feature causing existing functionality to break)
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Additional information

• This PR fixes or closes issue: fixes #
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[home-assistant]

Hey there @frenck, mind taking a look at this pull request as it has been labeled with an integration (radio_browser) you are listed as a code owner for? Thanks!

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[cdce8p]

pycountry is a separate dependency and as such should probably be imported directly. Added it to manifest.json as well.