Remove deprecated Lua tbl_flatten

nvim/.config/nvim/lua/yock/plugins/neotest.lua

@@ -7,6 +7,7 @@ return {
     'nvim-treesitter/nvim-treesitter',
     'olimorris/neotest-rspec',
   },
+  lazy = true,
   config = function()
     local neotest = require('neotest')
     local rspec = require('neotest-rspec')
@@ -18,9 +19,7 @@ return {
 
     rspec({
       rspec_cmd = function()
-        return vim.tbl_flatten({
-          'bin/rspec',
-        })
+        return 'bin/rspec'
       end
     })