What's Changed
* Add XPP to engines; to v0.2.21 by pgleeson in https://github.com/OpenSourceBrain/osb-model-validation/pull/121
* XPP updates: Add JNeuroMLXppEngine and pyNEURON_XPP_LEMS by pgleeson in https://github.com/OpenSourceBrain/osb-model-validation/pull/122
**Full Changelog**: https://github.com/OpenSourceBrain/osb-model-validation/compare/v0.2.20...v0.2.21