Tenant matching query does not exist.

Requirements:
```
Django==4.2
django-multitenant==4.0.0
```

Python version: `3.9`

My models look like this:
```
# Django
from django.db import models

# Utils
from django_multitenant.fields import TenantForeignKey
from django_multitenant.models import TenantModel

class BaseModel(TenantModel):
""" Base model

Act as an abstract model and all the models in the project should inherit from it.
"""

created = models.DateTimeField(
'created at',
auto_now_add=True,
help_text='Date time on which the object was created.'
)

modified = models.DateTimeField(
'modified at',
auto_now=True,
help_text='Date time on which the object was modified.'
)

deleted = models.BooleanField(
default=False,
help_text='Set to True when an element is deleted'
)

tenant = TenantForeignKey(Tenant,
on_delete=models.CASCADE,
related_name='%(app_label)s_%(class)s_related',
null=True)

class Meta:
abstract = True
get_latest_by = 'created'
ordering = ['-created', '-modified']

class TenantMeta:
tenant_field_name = "tenant_id"

class User(AbstractUser, BaseModel):
pass

class Tenant(TenantModel):
"""
Tenant model.
"""
unique_id = models.UUIDField(unique=True, null=False, blank=False)
name = models.CharField(max_length=500, null=False, blank=False)

class TenantMeta:
tenant_field_name = "id"
```

And my middleware looks like this:
```
class MultiTenantMiddleware:
def __init__(self, get_response):
self.get_response = get_response

def __call__(self, request):
if request.user and not request.user.is_anonymous:
set_current_tenant(request.user.tenant)

return self.get_response(request)
```

When I'm logged at the same time with two different users that belong to a different tenant and interact within the Django admin with both users almost at the same time, one of the sessions starts to throw this exception:

```
Internal Server Error: /secure/admin/api/imagepool/
Traceback (most recent call last):
File "/usr/local/lib/python3.9/site-packages/django/db/models/fields/related_descriptors.py", line 218, in __get__
rel_obj = self.field.get_cached_value(instance)
File "/usr/local/lib/python3.9/site-packages/django/db/models/fields/mixins.py", line 15, in get_cached_value
return instance._state.fields_cache[cache_name]
KeyError: 'tenant'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/usr/local/lib/python3.9/site-packages/django/core/handlers/exception.py", line 55, in inner
response = get_response(request)
File "/app/api/middleware/tenant_middleware.py", line 55, in __call__
tenant = get_user_tenant(request)
File "/app/api/middleware/tenant_middleware.py", line 16, in get_user_tenant
return request.user.tenant
File "/usr/local/lib/python3.9/site-packages/django/utils/functional.py", line 268, in inner
return func(_wrapped, *args)
File "/usr/local/lib/python3.9/site-packages/django/db/models/fields/related_descriptors.py", line 236, in __get__
rel_obj = self.get_object(instance)
File "/usr/local/lib/python3.9/site-packages/django/db/models/fields/related_descriptors.py", line 199, in get_object
return qs.get(self.field.get_reverse_related_filter(instance))
File "/usr/local/lib/python3.9/site-packages/django/db/models/query.py", line 637, in get
raise self.model.DoesNotExist(
tenant.models.tenant.Tenant.DoesNotExist: Tenant matching query does not exist.
```

And that even happens with just one user at the time if I start doing too many requests to the server in a short period of time... And even with normal usage and just one user at the time sometimes I get that error.