Temp. silence deprecation warnings in test env

Give Travis CI a break.

Signed-off-by: Alex Coles <alex@alexbcoles.com>

config/environments/test.rb

@@ -65,7 +65,7 @@ OpenProject::Application.configure do
   config.active_record.mass_assignment_sanitizer = :strict
 
   # Print deprecation notices to the stderr
-  config.active_support.deprecation = :stderr
+  config.active_support.deprecation = :silence
 
   # we use per process memory for caching in the test environment
   config.cache_store = :memory_store