Jewish Calendar: Implement diagnostics

[tsvi]

Breaking change

Proposed change

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 #
• This PR is related to issue: Jewish Calendar quality scale #143763
• Link to documentation pull request:
• Link to developer documentation pull request:
• Link to frontend pull request:

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[epenet]

I think diagnostics require 100% coverage

[home-assistant]

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

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tests are there