Fixed codeception version in travis.yml

Author: dmeroff

.travis.yml

@@ -21,7 +21,7 @@ cache:
 # install dependencies
 install:
   - travis_retry composer self-update
-  - travis_retry composer global require "codeception/codeception:2.2.x@dev"
+  - travis_retry composer global require "codeception/codeception:2.2.5"
   - travis_retry composer global require "fxp/composer-asset-plugin:~1.1.0"
   - travis_retry composer install --prefer-dist