Run GC from test setup

I have seen a test run where the "connected_clients" field in the INFO output
changed from 15 to 3 over a statement where GC might run. This change should
prevent that from happening again.

Author: pietern

test/helper.rb

@@ -141,6 +141,9 @@ module Generic
     def setup
       @log = StringIO.new
       @redis = init _new_client
+
+      # Run GC to make sure orphaned connections are closed.
+      GC.start
     end
 
     def teardown