chore: remove unused param from extractRequiredReferenceProperties

[nickajacks1]

Added in 713aeecdfa, appears to have never been used.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.64%. Comparing base (4d074c3) to head (762cdb8). Report is 7 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #335 +/- ## ========================================== - Coverage 99.65% 99.64% -0.02% ========================================== Files 164 164 Lines 16674 16674 ========================================== - Hits 16616 16614 -2 - Misses 53 55 +2 Partials 5 5 ``` | [Flag](https://app.codecov.io/gh/pb33f/libopenapi/pull/335/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pb33f) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/pb33f/libopenapi/pull/335/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pb33f) | `99.64% <100.00%> (-0.02%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pb33f#carryforward-flags-in-the-pull-request-comment) to find out more.

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[daveshanley]

cool.