bim.refresh_library - add missing undo flag

It's unsafe in Blender to leave operators that edit blend data without undo flag.

src/bonsai/bonsai/bim/module/project/operator.py

@@ -210,6 +210,7 @@ class SelectLibraryFile(bpy.types.Operator, IFCFileSelector):
 class RefreshLibrary(bpy.types.Operator):
     bl_idname = "bim.refresh_library"
     bl_label = "Refresh Library"
+    bl_options = {"UNDO"}
 
     def execute(self, context):
         self.props = tool.Project.get_project_props()