Adjust async_step_homekit signature for strict typing

[epenet]

Proposed change

Adjust async_step_homekit type hint, as follow-up to #59503

See home-assistant/architecture#662

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
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• This PR fixes or closes issue: fixes #
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[probot-home-assistant]

Hey there @milanmeu, mind taking a look at this pull request as it has been labeled with an integration (nanoleaf) you are listed as a code owner for? Thanks!
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[probot-home-assistant]

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[bdraco]

Test failure is unrelated and fixed in #59749

[janiversen]

LGTM.