Fix isort import order and add requirements.txt for Spark ask-and-tell example

Author: Dhyey Findoriya

spark/ask_and_tell_spark.py

@@ -9,6 +9,7 @@
 
 import optuna
 
+
 try:
     from pyspark.sql import SparkSession
 except ImportError:
@@ -25,7 +26,6 @@ def evaluate(x):
     else:
         spark = SparkSession.builder.appName("OptunaSparkExample").getOrCreate()
         study = optuna.create_study()
-        optuna.seed(42)
 
         for i in range(20):
             trial = study.ask()

spark/requirements.txt

@@ -0,0 +1,2 @@
+optuna
+pyspark  # used for SparkSession and RDD parallelism