Adhere to style guide

Signed-off-by: Viranch Mehta <viranch.mehta@gmail.com>

Author: viranch

compose/service.py

@@ -679,7 +679,7 @@ def labels(self, one_off=False):
 
     def can_be_scaled(self):
         for port in self.options.get('ports', []):
-            if ':' in str(port) and not '::' in str(port):
+            if ':' in str(port) and '::' not in str(port):
                 return False
         return True