Bump flux_led to 0.28.4 to fix setting white temp on 0x35 devices

[bdraco]

Proposed change

• Changelog: Danielhiversen/flux_led@0.28.3...0.28.4

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)
• Code quality improvements to existing code or addition of tests

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

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