Remove iter_mut impl on Occupant

Signed-off-by: Maxime “pep” Buquet <pep@bouah.net>

src/types.rs

@@ -157,10 +157,6 @@ impl Occupant {
     fn iter(&self) -> std::slice::Iter<'_, FullJid> {
         self.sessions.iter()
     }
-
-    fn iter_mut(&mut self) -> std::slice::IterMut<'_, FullJid> {
-        self.sessions.iter_mut()
-    }
 }
 
 pub(crate) static mut ROOMS: LazyLock<Mutex<HashMap<BareJid, Room>>> =