[Bug] Fix use of wrong function

[jadonwb]

Due to the change from #14 in init.lua:

-            require("bento.ui").refresh_menu()
+            require("bento.ui").render_expanded()

I get the error "attempt to reference nil value", as render_expanded() is a local function for ui.lua.

Changing this back to refresh_menu() fixes the issue.

[waldnzwrld]

I agree with this, and it's absolutely my fault. For some reason my configuration was not erroring while testing, likely due to a missed sourcing or reload. Apologies. @serhez can we merge this?

[nikmcphail]

Would love for this to get merged, just discovered this plugin and its great but getting an error every buffer close is not ideal.