Get some pytest fixtures working with some side effects

jedi/plugins/registry.py

@@ -4,7 +4,8 @@ This is not a plugin, this is just the place were plugins are registered.
 
 from jedi.plugins import stdlib
 from jedi.plugins import flask
+from jedi.plugins import pytest
 from jedi.plugins import plugin_manager
 
 
-plugin_manager.register(stdlib, flask)
+plugin_manager.register(stdlib, flask, pytest)