tests: clear cache between tests (#30458)

tests/conftest.py

@@ -4,6 +4,7 @@ from httmock import urlmatch, HTTMock, response
 import django_webtest
 
 from django.core.files import File
+from django.core.cache import cache
 from io import BytesIO
 
 from .utils import make_resource
@@ -14,6 +15,7 @@ def app(request):
     wtm = django_webtest.WebTestMixin()
     wtm._patch_settings()
     request.addfinalizer(wtm._unpatch_settings)
+    cache.clear()
     return django_webtest.DjangoTestApp()