Prevent workers terminal summary for syrypy.

Unregister syrupy in pytest_session_finish for xdist workers so that
syrupy does not run its pytest_terminal_summary hook.

Author: paul-ollis

pytest_textual_snapshot.py

@@ -290,6 +290,11 @@ def pytest_sessionfinish(
         diffs, num_snapshots_passing = retrieve_svg_diffs(tempdir)
         save_svg_diffs(diffs, session, num_snapshots_passing)
         tempdir.cleanup()
+    else:
+        config = session.config
+        plugin_manager = config.pluginmanager
+        syrupy = plugin_manager.getplugin('syrupy')
+        plugin_manager.unregister(syrupy)
 
 
 def retrieve_svg_diffs(