CompatHelper: bump compat for PosDefManifold to 0.5, (keep existing compat)

[github-actions[bot]]

This pull request changes the compat entry for the PosDefManifold package from 0.4.9 to 0.4.9, 0.5. This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry. It is your responsibility to make sure that your package tests pass before you merge this pull request.