fix(deps): update dependency nldoc_spec to v1.3.9

See merge request toegang-voor-iedereen/backend/lib/nldoc_conversion_writer_html!25

## [1.2.10](toegang-voor-iedereen/backend/lib/nldoc_conversion_writer_html@1.2.9...1.2.10) (2025-04-02)

### Bug Fixes

* **deps:** update dependency nldoc_spec to v1.3.9 ([ee5d8f16](toegang-voor-iedereen/backend/lib/nldoc_conversion_writer_html@ee5d8f16))