nvim: treesitter: Fix incorrect file reference for lean

nvim/.config/nvim/lua/treesitter.lua

@@ -50,7 +50,7 @@ require "nvim-treesitter.parsers".get_parser_configs().lean = {
   filetype     = "lean",
   install_info = {
     url   = "~/GitSources/tree-sitter-lean",
-    files = {"src/parser.c", "src/scanner.cc"},
+    files = {"src/parser.c", "src/scanner.c"},
   },
 }