fix(picker): do not record consecutive duplicate history (#2040)

## Description

Before this fix, identical items are added to history repeatedly. This
PR fixes this by only adding an item to history if it's different from
the last recorded value.

This doesn't completely remove duplicate entries in the history, it only
prevents consecutive identical entries.

lua/snacks/picker/util/history.lua

@@ -53,6 +53,10 @@ function M:is_current()
 end
 
 function M:record(value)
+  -- don't record value if it's identical to the last recorded value
+  if vim.deep_equal(self.kv:get(math.max(self.idx - 1, 1)), value) then
+    return
+  end
   self.kv:set(self.idx, value)
 end