Add ts grammar to the dependencies

[pleshevskiy]

I install milisims/tree-sitter-org manually and I make sure I use latest version (081179c52b3e8175af62b9b91dc099d010c38770).

On startup orgmode plugin fails with the following error:

[orgmode] You are using outdated version of tree-sitter grammar for Orgmode.
To use latest version, replace current grammar installation with "require('orgmode').setup_ts_grammar()" and run :TSUpdate org.
More info in setup section of readme: https://github.com/nvim-orgmode/orgmode#setup

Because my org-parser don't have a revision field.

:lua print(vim.inspect(require('nvim-treesitter.parsers').get_parser_configs().org));
{
  install_info = {
    branch = "main",
    files = { "src/parser.c", "src/scanner.cc" },
    url = "https://github.com/milisims/tree-sitter-org"
  },
  <metatable> = {
    __newindex = <function 1>
  }
}

I made a patch removing grammar checker, but I think we can add milisims/tree-sitter-org to the dependencies in the readme or to make some kind of relaxation to the check.

[kristijanhusak]

We are using a specific grammar version to make sure nothing breaks, since grammar is not used only for highlighting, as it is the case in most of the other grammars. If you want to provide custom commit hash for any reason, do it like this:

require('orgmode').setup_ts_grammar('custom_hash_here')