Remove get_random_64()

Its uses are replaced by get_randm_bytes() or encode_random_bytes().

src/db/models/user.rs

@@ -93,7 +93,7 @@ impl User {
             email_new_token: None,
 
             password_hash: Vec::new(),
-            salt: crypto::get_random_64(),
+            salt: crypto::get_random_bytes::<64>().to_vec(),
             password_iterations: CONFIG.password_iterations(),
 
             security_stamp: crate::util::get_uuid(),