fix!: Use new treesitter foldexpr() method from main branch

Author: Allaman

lua/vnext/config/options.lua

@@ -10,10 +10,10 @@ o.expandtab      = true                                            -- use spaces
 o.diffopt        = "internal,filler,closeoff,linematch:60"         -- improve diff visualization
 o.fillchars      = "eob: ,fold: ,foldopen:,foldsep: ,foldclose:" -- hide ~ at the end of buffer and set fold symbols
 o.foldenable = true                                                -- enable folding
-o.foldexpr = "nvim_treesitter#foldexpr()"
+o.foldmethod = "expr"
+o.foldexpr = "v:lua.vim.treesitter.foldexpr()"
 o.foldlevel = 99
 o.foldlevelstart = -1                                               -- top level folds only are closed by default
-o.foldmethod = "expr"
 o.foldnestmax = 4                                                  -- max level of folds
 o.foldtext = ""
 o.ignorecase     = true                                            -- ignore case in search patterns