Added test_server_time.py

Author: Trivium0911

integration_tests/rest/test_24h_price_change.py

@@ -0,0 +1,9 @@
+class TestServerTime:
+
+    def test_response_corresponds_swagger_schema(self, client):
+        resp_keys = ['serverTime']
+        server_time = client.get_server_time()
+        assert len(server_time) == 1
+        assert type(server_time) is dict
+        assert all(key in resp_keys for key in server_time)
+        assert all(server_time[key] is not None for key in server_time)