Un-used import statement removed

The "getcurrent" function was not used in the example.
Signed-off-by: Balthazar Rouberol <rouberol.b@gmail.com>

Author: Balthazar Rouberol

tutorial.md

@@ -804,7 +804,6 @@ tasks in parallel.
 
 [[[cog
 import gevent
-from gevent import getcurrent
 from gevent.pool import Pool
 
 pool = Pool(2)