nix lsp update

lua/plugins/conform.lua

@@ -4,6 +4,7 @@ return {
     require("conform").setup({
       formatters_by_ft = {
         lua = { "stylua" },
+        nix = { "nixfmt" },
         python = function(bufnr)
           if require("conform").get_formatter_info("ruff_format", bufnr).available then
             return { "ruff_fix", "ruff_format" }

lua/plugins/lsp.lua

@@ -74,6 +74,7 @@ return {
       jqls = {},
       jsonls = {},
       marksman = {},
+      nil_ls = {},
       pyright = {
         python = {
           analysis = {
@@ -83,7 +84,6 @@ return {
           },
         },
       },
-      rnix = {},
       rust_analyzer = {
         diagnostics = {
           enable = true,