Handle invalid utf-8 from the ESPHome dashboard

[bdraco]

Proposed change

If the yaml file has invalid utf-8, the config flow would raise an unhandled exception. Allow the encryption key to be entered manually in this case instead of a hard failure

fixes #92772

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

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

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