[pre-commit.ci] auto fixes from pre-commit.com hooks

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tests/test_backends.py

@@ -4,11 +4,7 @@
 import numpy as np
 import pytest
 from qibo import Circuit, gates
-from qibo.backends import (
-    NumpyBackend,
-    list_available_backends,
-    set_backend,
-)
+from qibo.backends import NumpyBackend, list_available_backends, set_backend
 from qibo.quantum_info import random_clifford
 
 from qibo_cloud_backends import (