Use kwargs for creating workers in es_trainer_lib

\#453 made keyword arguments required for instantiating worker managers. The
callsite in es_trainer_lib was never updated, so updating it now to get things
working for ES.

Given this was not caught in CI, it might be worth having better typing for the
worker managers so that this is caught earlier.

Author: boomanaiden154

compiler_opt/es/es_trainer_lib.py

@@ -213,7 +213,7 @@ def train(additional_compilation_flags=(),
 
   with worker_manager_class(
       worker_class,
-      learner_config.total_num_perturbations,
+      count=learner_config.total_num_perturbations,
       worker_kwargs=dict(gin_config=gin.operative_config_str())) as pool:
     for _ in range(learner_config.total_steps):
       learner.run_step(pool)