CI: freeze docs requirements [hotfix] (#15865)

freeze ipy

Author: Borda

requirements/pytorch/docs.txt

@@ -1,6 +1,6 @@
 -r ../docs.txt
 
-ipython[notebook]
+ipython[notebook] <8.7.0
 setuptools<58.0  # workaround for `error in ipython setup command: use_2to3 is invalid.`
 pt-lightning-sphinx-theme @ https://github.com/Lightning-AI/lightning_sphinx_theme/archive/master.zip