chore(nvim): cleaned config a bit

.config/nvim/lua/plugins/none-ls.lua

@@ -3,12 +3,8 @@ local null_ls = require("null-ls")
 
 null_ls.setup({
     sources = {
-        null_ls.builtins.formatting.rustfmt,
         null_ls.builtins.formatting.black,
-        null_ls.builtins.diagnostics.flake8,
         null_ls.builtins.formatting.gofmt,
-        null_ls.builtins.code_actions.shellcheck,
-        null_ls.builtins.formatting.beautysh,
         null_ls.builtins.formatting.prettierd.with({
             filetypes = { "html", "json", "css", "js", "yaml", "markdown" },
         }),