Remove trailing whitespace

Author: jmikola

.travis.yml

@@ -16,7 +16,7 @@ matrix:
     - php: 5.5
       env: &common_env DRIVER_VERSION=1.3.3 SERVER_VERSION=3.4
       addons: &common_addons
-        apt: 
+        apt:
           sources: [ mongodb-3.4-precise ]
           packages: [ mongodb-org, *common_packages ]
     - php: 5.6