python310Packages.monai: unbreak

Upstream added a `monai[ninja]` install option and a corresponding
`ninja = ` in `setup.cfg`, which broke a previous hack around
`setuptools` not detecting `ninja` correctly.

Changed files
+1 -1
pkgs
development
python-modules
monai
+1 -1
pkgs/development/python-modules/monai/default.nix
···
# Ninja is not detected by setuptools for some reason even though it's present:
postPatch = ''
-
substituteInPlace "setup.cfg" --replace "ninja" ""
+
substituteInPlace "setup.cfg" --replace " ninja" ""
'';
preBuild = ''