Description

Attempting to change the address of a WireGuard network results in error even though the new address is the same prefix length as the previous one and should accommodate the same number of devices.

Steps to Reproduce

1. Create a WireGuard network with address 10.1.1.0/29 (8 addresses, 5 usable
   host slots)
2. Connect a gateway to the network
3. Create a user and add 5 devices to them — the network is now completely
   full
4. Try to change the network address to another /29, e.g. 12.1.1.0/29

Cause (?)

let mut allowed_devices = location.get_allowed_devices(&mut *conn).await?;  // 5 user devices
let network_devices =
    Device::find_by_type_and_network(&mut *conn, DeviceType::Network, location.id).await?;
allowed_devices.extend(network_devices);  // + 1 gateway device = 6

let count = allowed_devices.len() + 3;   // 6 + 3 = 9
location.validate_network_size(count)?;  // 9 > 8 (size of /29) -> error