Error
Traceback (most recent call last):
  File "/home/radoslaw/PycharmProjects/django_school/tests/lessons/test_views.py", line 267, in test_updates_lesson_session_and_presences
    self.client.post(self.get_url(), data=data)
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/test/client.py", line 751, in post
    response = super().post(path, data=data, content_type=content_type, secure=secure, **extra)
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/test/client.py", line 407, in post
    return self.generic('POST', path, post_data, content_type,
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/test/client.py", line 473, in generic
    return self.request(**r)
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/test/client.py", line 719, in request
    self.check_exception(response)
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/test/client.py", line 580, in check_exception
    raise exc_value
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/core/handlers/base.py", line 181, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/contrib/auth/decorators.py", line 21, in _wrapped_view
    return view_func(request, *args, **kwargs)
  File "/home/radoslaw/PycharmProjects/django_school/django_school/apps/common/utils.py", line 20, in wrapper
    return func(request, *args, **kwargs)
  File "/home/radoslaw/PycharmProjects/django_school/django_school/apps/lessons/views.py", line 119, in lesson_session_detail_view
    lesson_session_form.save()
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/forms/models.py", line 468, in save
    self.instance.save()
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/db/models/base.py", line 726, in save
    self.save_base(using=using, force_insert=force_insert,
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/db/models/base.py", line 763, in save_base
    updated = self._save_table(
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/db/models/base.py", line 845, in _save_table
    updated = self._do_update(base_qs, using, pk_val, values, update_fields,
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/db/models/base.py", line 899, in _do_update
    return filtered._update(values) > 0
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/db/models/query.py", line 802, in _update
    return query.get_compiler(self.db).execute_sql(CURSOR)
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1559, in execute_sql
    cursor = super().execute_sql(result_type)
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1162, in execute_sql
    sql, params = self.as_sql()
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1525, in as_sql
    val = field.get_db_prep_save(val, connection=self.connection)
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/db/models/fields/__init__.py", line 842, in get_db_prep_save
    return self.get_db_prep_value(value, connection=connection, prepared=False)
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/db/models/fields/__init__.py", line 1271, in get_db_prep_value
    value = self.get_prep_value(value)
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/db/models/fields/__init__.py", line 1266, in get_prep_value
    return self.to_python(value)
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/db/models/fields/__init__.py", line 1228, in to_python
    parsed = parse_date(value)
  File "/home/radoslaw/.local/share/virtualenvs/django_school-b1r-K0kH/lib/python3.8/site-packages/django/utils/dateparse.py", line 75, in parse_date
    match = date_re.match(value)
TypeError: expected string or bytes-like object