cad/openvsp: Update to 3.50.3
ChangeLog:
https://openvsp.org/blogs/announcements/2026/05/15/openvsp-3-50-3-released
- Fix corrupt XML file output with vectors of vec3d’s
- Fix crash when changing XSec type when CEdit screen still open
- Fix problem reading VSPAERO results that caused ghost results
- Write full precision in files sent to VSPAERO