Fix doc requirements

doc/doc-requirements.txt

@@ -1,16 +1,19 @@
+--extra-index-url https://download.pytorch.org/whl/cu118
 joblib
+matplotlib
+memory_profiler
+mne
+nilearn
 numpy
 numpydoc
-matplotlib
 pandas
 pillow
+PyQt5
+pyvista
+pyvistaqt
 scikit-learn
 scipy
 sphinx-bootstrap-theme
 sphinx-gallery
-mne
-pyvista
-pyvistaqt
-PyQt5
-nilearn
-memory_profiler
+torch
+torchmetrics