Using proper format for 2.6

Author: djw8605

bin/stashcp

@@ -407,7 +407,7 @@ def get_best_stashcache():
     append_text = "api/v1.0/geo/stashcp"
 
     # Headers for the HTTP request
-    headers = {'Cache-control': 'max-age=0', 'User-Agent': 'stashcp/%s' % VERSION }
+    headers = {'Cache-control': 'max-age=0', 'User-Agent': 'stashcp/{0}'.format(VERSION) }
 
     # Randomize the geo ip sites
     random.shuffle(geo_ip_sites)