Update rand to 0.9

[JonathanWoollett-Light]

No description provided.

[paolobarbolini]

This doesn't fix deprecation warnings:

warning: use of deprecated function `secure::rand::thread_rng`: Renamed to `rng`
   --> src/secure/key.rs:142:44
    |
142 |         let mut rng = crate::secure::rand::thread_rng();
    |                                            ^^^^^^^^^^
    |
    = note: `#[warn(deprecated)]` on by default

warning: use of deprecated function `secure::rand::thread_rng`: Renamed to `rng`
  --> src/secure/private.rs:53:35
   |
53 |         let mut rng = self::rand::thread_rng();
   |

[JonathanWoollett-Light]

@paolobarbolini Fixed.