input: Write a python function to load a CSV file into a pandas DataFrame, generate summary statistics, and save the summary statistics to an HTML file.
  assert generate_summary_report('orders.csv', 'report.html') == None
  assert generate_summary_report('test_data.csv', 'test_report.html') == None
output: def generate_summary_report(csv_file, html_file):
      import pandas as pd
      
      # Load the CSV file into a DataFrame
      df = pd.read_csv(csv_file)
      
      # Generate summary statistics
      summary_stats = df.describe()
      
      # Save the summary statistics to an HTML file
      summary_stats.to_html(html_file)