Version constant php7.4+ (#52)

fixes #49

Author: ferhatelmas

lib/GetStream/StreamChat/Client.php

@@ -11,7 +11,10 @@
 use GuzzleHttp\Psr7\Uri;
 use GuzzleHttp\Psr7\MultipartStream;
 
-const VERSION = '2.1.0';
+class Constant
+{
+    const VERSION = '2.1.0';
+}
 
 class Client
 {
@@ -166,7 +169,7 @@ protected function getHttpRequestHeaders()
             'Authorization' => $this->authToken,
             'Content-Type' => 'application/json',
             'stream-auth-type' => 'jwt',
-            'X-Stream-Client' => 'stream-chat-php-client-' . VERSION,
+            'X-Stream-Client' => 'stream-chat-php-client-' . Constant::VERSION,
         ];
     }