Clear cache for get_user_environment_variables when changing system to ensure next call will retrieve the new change

Author: mrclary

Diff for: spyder/utils/environ.py

@@ -170,9 +170,11 @@ def set_user_env(env, parent=None):
                   "Please restart this Windows <i>session</i> "
                   "(not the computer) for changes to take effect.")
             )
+        get_user_environment_variables.cache_clear()
     elif os.name == 'posix' and running_in_ci():
         text = "\n".join([f"export {k}={v}" for k, v in env_dict.items()])
         amend_user_shell_init(text)
+        get_user_environment_variables.cache_clear()
     else:
         raise NotImplementedError("Not implemented for platform %s", os.name)