fix(picker): dont watch files for closed pickers. Fixes #2365

lua/snacks/picker/core/picker.lua

@@ -64,6 +64,7 @@ function M.get(opts)
   for picker in pairs(M._active) do
     local want = (not opts.source or picker.opts.source == opts.source)
       and (opts.tab == false or picker:on_current_tab())
+      and not picker.closed
     if want then
       ret[#ret + 1] = picker
     end