Added isort nullls and move it to lsp installer file

init.lua

@@ -178,13 +178,3 @@ require("indent_blankline").setup {
   context_patterns = {'class', 'function', 'method', 'block', '^if', '^for', '^while'},
 }
 
-local null_ls = require("null-ls")
-null_ls.setup {
-  sources = {
-    null_ls.builtins.code_actions.gitsigns,
-    null_ls.builtins.formatting.autopep8,
-    null_ls.builtins.formatting.prettier,
-    null_ls.builtins.formatting.stylua,
-    null_ls.builtins.diagnostics.flake8
-  }
-}