forgot to make changes in tests aswell as add the correct slot for breakpoint

src/simudator/core/breakpoint.py

 class Breakpoint:
 
-    __slots__ = "_is_enabled"
+    __slots__ = "is_enabled"
     """
     Base class for beakpoints, intended to be subclassed.
 

test/test_core/test_mux.py

@@ -38,7 +38,6 @@ def test_get_state():
     assert state["name"] == "Mux"
     assert state["value"] == 7
     assert state["bit_length"] == 5
-    assert state["mask"] == 31
 
 
 def test_set_state():
@@ -58,9 +57,8 @@ def test_set_state():
     mux.set_state(state)
 
     assert mux.name == "Mux"
-    assert mux.value == 6
-    assert mux.bit_length == 2
-    assert mux.mask == 3
+    assert mux._value == 6
+    assert mux._bit_length == 2
 
 
 def test_writing_to_output():