vyconf: T6718: add keyword default for change in libvyosconfig binding

[jestabro]

Change Summary

Adjust signature of reference_tree_to_json for change in the ctypes binding.

Split off commit from #4176 to solve a chicken-egg problem with the change in signature of reference_tree_to_json after merge of vyos-legacy/libvyosconfig#21 and resulting update in vyos/vyos-build#824

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

Related PR(s)

Component(s) name

Proposed changes

How to test

Smoketest result

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[github-actions]

👍
No issues in PR Title / Commit Title

[jestabro]

N.B. this will not build until the commit hash for libvyosconfig is updated in
vyos/vyos-build#824
and that PR merged, at which point it will be required for successful build.

[jestabro]

Open for review, but as noted above, this will not build, nor should be merged, until merge of vyos/vyos-build#824

[github-actions]

CI integration 👍 passed!

Details

CI logs

• CLI Smoketests (no interfaces) 👍 passed
• CLI Smoketests (interfaces only) 👍 passed
• Config tests 👍 passed
• RAID1 tests 👍 passed
• TPM tests 👍 passed