Revert tokenizers (#423)

* Revert "fix: add missing "with" in README"

This reverts commit bf1e7f1f17.

* Revert "feat: tokenizers (#407)"

This reverts commit d2095ba267.

lua/avante/providers/copilot.lua

@@ -127,7 +127,6 @@ end
 M.state = nil
 
 M.api_key_name = P.AVANTE_INTERNAL_KEY
-M.tokenizer_id = "gpt-4o"
 
 M.parse_message = function(opts)
   return {
@@ -167,7 +166,6 @@ M.setup = function()
     M.state = { github_token = nil, oauth_token = H.get_oauth_token() }
     H.refresh_token()
   end
-  require("avante.tokenizers").setup(M.tokenizer_id)
   vim.g.avante_login = true
 end