Fix Target class [Gathuku\Mpesa\InstallMpesa] does not exist.

Import  use Gathuku\Mpesa\Console\InstallMpesa to the service provider

src/MpesaServiceProvider.php

@@ -3,6 +3,7 @@
 namespace Gathuku\Mpesa;
 
 use Illuminate\Support\ServiceProvider;
+use Gathuku\Mpesa\Console\InstallMpesa;
 
 class MpesaServiceProvider extends ServiceProvider
 {