replace settings=None with {}

src/ifcopenshell-python/ifcopenshell/api/group/assign_group.py

@@ -4,7 +4,7 @@ from ifcopenshell.api.owner.api import update_owner_history
 
 
 class Usecase:
-    def __init__(self, file, settings=None):
+    def __init__(self, file, settings={}):
         self.file = file
         self.settings = {
             "product": None,

src/ifcopenshell-python/ifcopenshell/api/group/edit_group.py

@@ -1,5 +1,5 @@
 class Usecase:
-    def __init__(self, file, settings=None):
+    def __init__(self, file, settings={}):
         self.file = file
         self.settings = {
             "group": None,

src/ifcopenshell-python/ifcopenshell/api/group/remove_group.py

@@ -1,5 +1,5 @@
 class Usecase:
-    def __init__(self, file, settings=None):
+    def __init__(self, file, settings={}):
         self.file = file
         self.settings = {"group": None}
         for key, value in settings.items():

src/ifcopenshell-python/ifcopenshell/api/group/unassign_group.py

@@ -3,7 +3,7 @@ from ifcopenshell.api.owner.api import update_owner_history
 
 
 class Usecase:
-    def __init__(self, file, settings=None):
+    def __init__(self, file, settings={}):
         self.file = file
         self.settings = {
             "product": None,