Fix state for empty key route

Replace None with Some("") for state_key

src/client_server/room.rs

@@ -195,7 +195,7 @@ pub fn create_room_route(
             content: match preset {
                 create_room::RoomPreset::PublicChat => {
                     serde_json::to_value(guest_access::GuestAccessEventContent::new(
-                        // In a public room a joining is the only way to access
+                        // In a public room, joining is the only way to access
                         guest_access::GuestAccess::Forbidden,
                     ))
                     .expect("event is valid, we just created it")

src/client_server/state.rs

@@ -76,7 +76,7 @@ pub fn send_state_event_for_empty_key_route(
             &body.content,
             json,
             &body.room_id,
-            None,
+            Some("".into()),
         )?
         .0
         .event_id,