feat: Expose NoUpdate type

Author: ytausch

dash/__init__.py

@@ -19,7 +19,7 @@
 from . import dash_table  # noqa: F401,E402
 from .version import __version__  # noqa: F401,E402
 from ._callback_context import callback_context, set_props  # noqa: F401,E402
-from ._callback import callback, clientside_callback  # noqa: F401,E402
+from ._callback import callback, clientside_callback, NoUpdate  # noqa: F401,E402
 from ._get_app import get_app  # noqa: F401,E402
 from ._get_paths import (  # noqa: F401,E402
     get_asset_url,
@@ -86,6 +86,7 @@ def _jupyter_nbextension_paths():
     "page_registry",
     "Dash",
     "no_update",
+    "NoUpdate",
     "page_container",
     "Patch",
     "jupyter_dash",