mgr/dashboard: add backport that allows the dashboard to work again

mgr/dashboard: add backport that allows the dashboard to work again

After upgrading from PVE 7 to PVE 8, some users noted that the Ceph
Dashboard does not work anymore. [0] A user from our community
provided a pull request [1] which removes a dependency to `PyJWT`
(Python). This commit adds a backport of this PR as a single patch.

This patch by itself however does not yet allow the dashboard to run
with TLS enabled.

[0]: https://forum.proxmox.com/threads/ceph-warning-post-upgrade-to-v8.129371/
[1]: https://github.com/ceph/ceph/pull/54710

Signed-off-by: Max Carrara <m.carrara@proxmox.com>