Revert "fix(ci): run all tests in workflow"

This reverts commit 4228222.

Author: denizozgur

.github/workflows/ci.yml

@@ -28,7 +28,4 @@ jobs:
       - name: Run tests
         run: |
           source venv/bin/activate
-          python backend/manage.py test outcomes
-          python backend/manage.py test users
-          python backend/manage.py test giraph
-          python backend/manage.py test programs
+          python backend/manage.py test