input: Write a python function to read student data from an Excel file and return a list of Student objects.
  assert len(read_excel('students.csv'))==3
  assert read_excel('students.csv')[0].name=='John Doe'
  assert read_excel('students.csv')[1].gpa==3.5
output: import pandas as pd
  
  class Student:
      def __init__(self, name, gpa):
          self.name = name
          self.gpa = gpa
  
  def read_excel(file_path):
      df = pd.read_csv(file_path)
      students = []
      for index, row in df.iterrows():
          student = Student(row['name'], row['gpa'])
          students.append(student)
      return students