fix(treesitter): fix ]c textobject mappings when in diff mode (#6911)

## Description
It seems that after
5985ca0cf1
the default `]c` Neovim mapping in diff mode broke. This is an attempt
to fix that.
<!-- Describe the big picture of your changes to communicate to the
maintainers
  why we should accept this pull request. -->

## Related Issue(s)
None, rather discussion #6910.
<!--
  If this PR fixes any issues, please link to the issue here.
  - Fixes #<issue_number>
-->

## Screenshots

<!-- Add screenshots of the changes if applicable. -->

## Checklist

- [x] I've read the
[CONTRIBUTING](https://github.com/LazyVim/LazyVim/blob/main/CONTRIBUTING.md)
guidelines.

lua/lazyvim/plugins/treesitter.lua

@@ -180,15 +180,16 @@ return {
             local desc = table.concat(parts, " or ")
             desc = (key:sub(1, 1) == "[" and "Prev " or "Next ") .. desc
             desc = desc .. (key:sub(2, 2) == key:sub(2, 2):upper() and " End" or " Start")
-            if not (vim.wo.diff and key:find("[cC]")) then
-              vim.keymap.set({ "n", "x", "o" }, key, function()
-                require("nvim-treesitter-textobjects.move")[method](query, "textobjects")
-              end, {
-                buffer = buf,
-                desc = desc,
-                silent = true,
-              })
-            end
+            vim.keymap.set({ "n", "x", "o" }, key, function()
+              if vim.wo.diff and key:find("[cC]") then
+                return vim.cmd("normal! " .. key)
+              end
+              require("nvim-treesitter-textobjects.move")[method](query, "textobjects")
+            end, {
+              buffer = buf,
+              desc = desc,
+              silent = true,
+            })
           end
         end
       end