tests: cleanup pytest config (#652)

Author: blueyed

setup.cfg

@@ -1,8 +1,9 @@
 [tool:pytest]
 # --strict: warnings become errors.
-# -r fEsxXw: show extra test summary info for everything.
-addopts = --ignore lib/ --ignore build/ --ignore include/ --ignore local/ --ignore src/ --strict -r fEsxXw
+# -ra: show extra test summary info for everything.
+addopts = --strict -ra
 DJANGO_SETTINGS_MODULE = pytest_django_test.settings_sqlite_file
+testpaths = tests
 
 [wheel]
 universal = 1