feat: include mount path in databag contents

[DanielArndt]

There's no need to infer the mount path, and adding it makes the interface more flexible.

This also bumps the libraries to their latest versions.

This conforms with the interface described in https://github.com/canonical/charm-relation-interfaces/tree/main/interfaces/vault_autounseal/v0

k8s charm version: https://github.com/canonical/vault-k8s-operator/pull/406

Checklist:

• [ ] My code follows the style guidelines of this project
• [ ] I have performed a self-review of my own code
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests that validate the behaviour of the software
• [ ] I validated that new and existing unit tests pass locally with my changes
• [ ] Any dependent changes have been merged and published in downstream modules