Bug: remove explicit set of PYSPARK_PYTHON (#193)

* remove explicit set of PYSPARK_PYTHON

* undo accidental change

aztk_sdk/spark/helpers/submit.py

@@ -56,7 +56,6 @@ def __app_submit_cmd(
         app + ' ' + ' '.join(app_args if app_args else []))
 
     docker_exec_cmd = CommandBuilder('sudo docker exec')
-    docker_exec_cmd.add_option('-e', 'PYSPARK_PYTHON=/usr/bin/python3')
     docker_exec_cmd.add_option('-i', constants.DOCKER_SPARK_CONTAINER_NAME)
     docker_exec_cmd.add_argument(spark_submit_cmd.to_str())