Drop features deprecated in Django 3.0

https://docs.djangoproject.com/en/dev/releases/3.0/#django-utils-encoding-force-text-and-smart-text

account/forms.py

@@ -4,8 +4,8 @@
 from django import forms
 from django.contrib import auth
 from django.contrib.auth import get_user_model
-from django.utils.encoding import force_text
-from django.utils.translation import gettext_lazy as _
+from django.utils.encoding import force_str
+from django.utils.translation import ugettext_lazy as _
 
 from account.conf import settings
 from account.hooks import hookset
@@ -25,7 +25,7 @@ def __init__(self, *args, **kwargs):
     def to_python(self, value):
         if value in self.empty_values:
             return ""
-        value = force_text(value)
+        value = force_str(value)
         if self.strip:
             value = value.strip()
         return value