fix: export required symbols

Co-authored-by: Midnighter <[email protected]>

Author: ilaif

src/structurizr/view/__init__.py

@@ -24,4 +24,6 @@
 from .animation import Animation, AnimationIO
 from .system_context_view import SystemContextView, SystemContextViewIO
 from .view_set import ViewSet, ViewSetIO
-from .element_style import ElementStyle
+from .element_style import ElementStyle, ElementStyleIO
+from .relationship_style import RelationshipStyle, RelationshipStyleIO
+from .configuration import Configuration, ConfigurationIO