Fix hvv departures authentication

[vigonotion]

Breaking change

Proposed change

The new orjson implementation causes jsons to be stripped of whitespaces, which causes the hvv departures authentication to fail because it computes a signature from the payload, which does not match the actual payload without whitespaces.

I changed pygti to use the json serializer from the session, which fixes this: https://github.com/vigonotion/pygti/releases/tag/v0.9.3

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)
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Additional information

• This PR fixes or closes issue: fixes HVV Departures integration - authentication failed since 2022.7.0 #74627
• This PR is related to issue:
• Link to documentation pull request:

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[frenck]

Thanks, @vigonotion 👍