input: Write a python function to calculate the average age of students from a given CSV file.
  assert calculate_average_age('students1.csv') == 20.5
  assert calculate_average_age('students2.csv') == 18.0
  assert calculate_average_age('students3.csv') == 22.3
output: import csv
  
  def calculate_average_age(file_name):
      with open(file_name, mode='r') as file:
          csv_reader = csv.DictReader(file)
          ages = [int(row['Age']) for row in csv_reader]
          average_age = sum(ages) / len(ages)
          return average_age