api: remove use of unnecessary pub(self)

api: remove use of unnecessary pub(self)

Fixes the clippy warning:

warning: unnecessary `pub(self)`
  --> src/api2/access/mod.rs:35:1
   |
35 | pub(self) async fn user_update_auth<S: AsRef<str>>(
   | ^^^^^^^^^ help: remove it
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_pub_self
   = note: `#[warn(clippy::needless_pub_self)]` on by default

Signed-off-by: Maximiliano Sandoval <m.sandoval@proxmox.com>