Fix readthedocs build #3948

Job	Run time
Run attacks_1 legacy (TensorFlow 2.10.1 Keras 2.10.0 PyTorch 1.13.1 scikit-learn 1.1.3 Python 3.9) Tests	56m 27s
Run attacks_1 legacy (TensorFlow 2.10.1 Keras 2.10.0 PyTorch 1.13.1 scikit-learn 1.1.3 Python 3.9) Tests	1h 8m 14s
Run attacks_2 legacy (TensorFlow 2.10.1 Keras 2.10.0 PyTorch 1.13.1 scikit-learn 1.1.3 Python 3.9) Tests	15m 44s
Run attacks_2 legacy (TensorFlow 2.10.1 Keras 2.10.0 PyTorch 1.13.1 scikit-learn 1.1.3 Python 3.9) Tests	15m 44s
Run estimators legacy (TensorFlow 2.10.1 Keras 2.10.0 PyTorch 1.13.1 scikit-learn 1.1.3 Python 3.9) Tests	6m 4s
Run estimators legacy (TensorFlow 2.10.1 Keras 2.10.0 PyTorch 1.13.1 scikit-learn 1.1.3 Python 3.9) Tests	7m 29s
Run defences legacy (TensorFlow 2.10.1 Keras 2.10.0 PyTorch 1.13.1 scikit-learn 1.1.3 Python 3.9) Tests	8m 46s
Run defences legacy (TensorFlow 2.10.1 Keras 2.10.0 PyTorch 1.13.1 scikit-learn 1.1.3 Python 3.9) Tests	8m 46s
Run metrics legacy (TensorFlow 2.10.1 Keras 2.10.0 PyTorch 1.13.1 scikit-learn 1.1.3 Python 3.9) Tests	6m 35s
Run metrics legacy (TensorFlow 2.10.1 Keras 2.10.0 PyTorch 1.13.1 scikit-learn 1.1.3 Python 3.9) Tests	6m 35s
Run art legacy (TensorFlow 2.10.1 Keras 2.10.0 PyTorch 1.13.1 scikit-learn 1.1.3 Python 3.9) Tests	5m 46s
Run art legacy (TensorFlow 2.10.1 Keras 2.10.0 PyTorch 1.13.1 scikit-learn 1.1.3 Python 3.9) Tests	5m 46s
	3h 31m 56s

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