Remove duplicate test

arkindex/ponos/tests/test_schema.py

-from django.core.management import call_command
-from django.test import TestCase
-
-
-class TestSchema(TestCase):
-    def test_generate_schema(self):
-        """
-        Runs the OpenAPI schema generation command, causing this test to fail if something goes wrong with the schema validation.
-        """
-        call_command(
-            "spectacular",
-            format="openapi-json",
-            fail_on_warn=True,
-            validate=True,
-        )