Fix google tasks due date timezone handling

[allenporter]

Proposed change

Fix google tasks due date timezone handling by always sending the date portion relative to UTC. The previous code would send the date in the local timestamp which would be on the wrong date when ignoring the time portion.

This was tested manually by changing the local datetime and observing the issue where the task moves to the wrong date.

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)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes Editing a todo list item due date and saving causes date to be out by one day. Google Tasks Integration. #125191
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
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• Tests have been added to verify that the new code works.

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[frenck]

Thanks, @allenporter 👍

../Frenck