fix: make test command

Unit test command was failing because manage.py was pointing to an
incorrect module by default.

manage.py

@@ -7,7 +7,7 @@
 import sys
 
 if __name__ == "__main__":
-    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "edxsearch.settings")
+    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "settings")
 
     from django.core.management import execute_from_command_line