Updated django settings to allow separating the storages used to store private and public keys:
JWT_PRIVATE_KEY_STORAGE
Storage class instance used to store JWT private signing key. Defaults to `"ninja_simple_jwt.jwt.key_store.local_disk_key_storage"`.
JWT_PUBLIC_KEY_STORAGE
Storage class instance used to store JWT public verification key. Defaults to `"ninja_simple_jwt.jwt.key_store.local_disk_key_storage"`.