www/py-dj51-drf-spectacular-sidecar: Update to 2025.4.1
- Switch to the PEP517 build framework.
Changelog:
https://github.com/tfranzel/drf-spectacular-sidecar/compare/2025.3.1...2025.4.1
MFH: 2025Q2
(cherry picked from commit f5112ee5310f159fe0a353282d4ceac1da20b434)