Cluster count missing from tenant api output
### NetBox version

3.1.5

### Python version

3.9

### Steps to Reproduce

Assign a Cluster to a Tenant. 
Retrieve Tenant details via API i.e. /api/tenancy/tenants/5/

### Expected Behavior

cluster_count is returned as part of the API response

### Observed Behavior

cluster_count is missing from the API response
diff --git a/netbox/tenancy/api/views.py b/netbox/tenancy/api/views.py
index 50b188b5f..c336c88b6 100644
--- a/netbox/tenancy/api/views.py
+++ b/netbox/tenancy/api/views.py
@@ -7,7 +7,7 @@ from ipam.models import IPAddress, Prefix, VLAN, VRF
 from tenancy import filtersets
 from tenancy.models import *
 from utilities.utils import count_related
-from virtualization.models import VirtualMachine
+from virtualization.models import VirtualMachine, Cluster
 from . import serializers
 
 
@@ -47,7 +47,8 @@ class TenantViewSet(CustomFieldModelViewSet):
         site_count=count_related(Site, 'tenant'),
         virtualmachine_count=count_related(VirtualMachine, 'tenant'),
         vlan_count=count_related(VLAN, 'tenant'),
-        vrf_count=count_related(VRF, 'tenant')
+        vrf_count=count_related(VRF, 'tenant'),
+        cluster_count=count_related(Cluster, 'tenant')
     )
     serializer_class = serializers.TenantSerializer
     filterset_class = filtersets.TenantFilterSet
['netbox/tenancy/api/views.py']