v0.9.18

Manifolds v0.9.18

Diff since v0.9.17

Added

• added the injectivity radius for the Stiefel manifold with Euclidean metric

Merged pull requests:

• Bump julia-actions/cache from 1 to 2 (#721) (@dependabot[bot])
• Implement infectivity radius on Stiefel (#722) (@kellertuer)

Closed issues:

• Implement a check_retraction function. (#599)