Updates guzzle request options (#40)

Request options save_to has been replaced by sink and removed in Guzzle 7.0

Author: michellaurent

src/GeoIPUpdater.php

@@ -71,7 +71,7 @@ protected function updateMaxmindDatabase()
         try {
             // Download database temp dir
             $tempFile = $tempDir.'/geoip';
-            $this->guzzle->get($maxmindDatabaseUrl, ['save_to' => $tempFile.'.tar.gz']);
+            $this->guzzle->get($maxmindDatabaseUrl, ['sink' => $tempFile.'.tar.gz']);
 
             $p = new PharData($tempFile.'.tar.gz');
             $p->decompress();