Update for v3.1.0

Author: oschwald

src/WebService/Client.php

@@ -58,7 +58,7 @@ class Client implements ProviderInterface
     private WsClient $client;
     private static string $basePath = '/geoip/v2.1';
 
-    public const VERSION = 'v3.0.0';
+    public const VERSION = 'v3.1.0';
 
     /**
      * Constructor.