Fixed WireGuard installation on Ubuntu when module is not built-in

- PIVPN_DEPS array should be assigned before appending to it,
    not after, to avoid overwriting existing items.

auto_install/install.sh

@@ -1336,11 +1336,12 @@ installWireGuard(){
 
 		echo "::: Installing WireGuard... "
 
+		PIVPN_DEPS=(wireguard-tools qrencode)
+
 		if [ "$WIREGUARD_BUILTIN" -eq 0 ]; then
 			PIVPN_DEPS+=(linux-headers-generic wireguard-dkms)
 		fi
 
-		PIVPN_DEPS=(wireguard-tools qrencode)
 		installDependentPackages PIVPN_DEPS[@]
 
 	fi