fix: add set_custom_exc to support a recent dask

In dask/dask#10354 dask
calls set_custom_exc to set a custom exception handler.

This breaks solara with dask because we have a custom/fake
IPython implementation.

Fixes #191

solara/server/patch.py

@@ -69,6 +69,10 @@ def magic(self, *args):
         # proplot requires this
         pass
 
+    def set_custom_exc(self, exc_tuple, handler):
+        # make dask work
+        pass
+
 
 def kernel_instance_dispatch(cls, *args, **kwargs):
     context = app.get_current_context()