How to avoid the "_csv.Error: iterator should return strings not bytes" error in a test class

When I run the following code I get an error message. This is my code:

import csv, unittest
from ddt import ddt, data, unpack
from selenium import webdriver
 
 
def get_data(file_name):
    # create an empty list to store rows
    rows = []
    # open the CSV file
    data_file = open(file_name, "rb")
    # create a CSV Reader from CSV file
    reader = csv.reader(data_file)
    # skip the headers
    next(reader, None)
    # add rows from reader to list
    for row in reader:
        rows.append(row)
    return rows
 
 
@ddt
class SearchCsvDDT(unittest.TestCase):
    def setUp(self):
        # create a new Firefox session
        self.driver = webdriver.Firefox()
        self.driver.implicitly_wait(30)
        self.driver.maximize_window()
 
        # navigate to the application home page
        self.driver.get('http://demo-store.seleniumacademy.com/')
 
    # get the data from specified csv file by calling the get_data function
    @data(*get_data('testdata.csv'))
    @unpack
    def test_search(self, search_value, expected_count):
        self.search_field = self.driver.find_element_by_name('q')
        self.search_field.clear()
 
        # enter search keyword and submit.
        self.search_field.send_keys(search_value)
        self.search_field.submit()
 
        # get all the anchor elements which have product names displayed
        # currently on result page using find_elements_by_xpath method
        products = self.driver \
            .find_elements_by_xpath("//h2[@class='product-name']/a")
        expected_count = int(expected_count)
        if expected_count > 0:
            # check count of products shown in results
            self.assertEqual(expected_count, len(products))
        else:
            msg = self.driver.find_element_by_class_name('note-msg')
            self.assertEqual('Your search returns no results.', msg.text)
 
    def tearDown(self):
        # close the browser window
        self.driver.quit()
 
if __name__ == '__main__':
    unittest.main(verbosity=2)

This is the error message I get:

File "test_search_func_with_csv.py", line 14, in get_data
    next(reader, None)
_csv.Error: iterator should return strings, not bytes (did you open the file in text mode?)

Why is it so? I have tried to apply the solutions shown here to no avail:_csv.Error: iterator should return strings, not bytes (did you open the file in text mode?)