Add circuittermination as a choice for cable endpoint types, which is not in the choices API for cable termination types but is accepted by the application as a valid endpoint for cables

netbox/dcim/constants.py

@@ -360,7 +360,7 @@ CONNECTION_STATUS_CHOICES = [
 
 # Cable endpoint types
 CABLE_TERMINATION_TYPES = [
-    'consoleport', 'consoleserverport', 'interface', 'poweroutlet', 'powerport', 'frontport', 'rearport',
+    'consoleport', 'consoleserverport', 'interface', 'poweroutlet', 'powerport', 'frontport', 'rearport', 'circuittermination',
 ]
 
 # Cable types