fix: post_set_venv not getting set in config

Because post_set_venv was nil is wasn't getting set in the config setup
table

Author: joshzcold

lua/python/config.lua

@@ -17,7 +17,7 @@ PythonConfig.defaults = {
   -- Path for venvs picker
   venvs_path = vim.fn.expand("~/.virtualenvs"),
   -- Something to do after setting an environment
-  post_set_venv = nil,
+  post_set_venv = false,
   -- base path for creating new venvs
   auto_create_venv_path = function(parent_dir)
     return vim.fs.joinpath(parent_dir, ".venv")