Allow only 4 maximum processes for pytest

This means it won't eat up all my CPUs locally.

pytest.ini

@@ -1,5 +1,5 @@
 [pytest]
-addopts = --ds=config.settings.test --reuse-db -n auto
+addopts = --ds=config.settings.test --reuse-db -n auto --maxprocesses 4
 python_files = tests.py test_*.py
 filterwarnings =
     # Convert all warnings to errors.