SageMath 10.5 new release

SageMath 10.5 has been released last week ; see the release tour
https://github.com/sagemath/sage/wiki/Sage-10.5-Release-Tour
for an overview of novelties and
https://sagemanifolds.obspm.fr/download.html
for short installation instructions. More extended ones are posted at
https://doc.sagemath.org/html/en/installation/

Regarding manifolds, SageMath 10.5 brings no new feature (only some corrected
typos in the documentation).

Everybody is very welcome to contribute to the SageManifolds project, please visit
https://sagemanifolds.obspm.fr/contrib.html