Bump sdk version

Author: z4kn4fein

src/ConfigCatClient.php

@@ -24,7 +24,7 @@
 final class ConfigCatClient
 {
     /** @var string */
-    const SDK_VERSION = "5.2.0";
+    const SDK_VERSION = "5.3.0";
 
     /** @var LoggerInterface */
     private $logger;