hash_remember_device_cookie_key method does raw translations from bytes to string

[sevdog]

The method hash_remember_device_cookie_key performs a raw casting from bytes to string:

django-two-factor-auth/two_factor/views/utils.py

Lines 293 to 294 in 52b78a7

	def hash_remember_device_cookie_key(otp_device_id):
	return str(base64.b64encode(force_bytes(otp_device_id)))

Thus the outputh of the method is something like b'....' which is probabilly not what it was supposed to produce.

To address this issue the casting may be changed by using force_str from django.utils.encoding.

This will have as a drawback that old cookies will not be validated, but it can be addressed in the validate_remember_device_cookie method by checking if the value starts with b' and ends with '.