Keras: fix build by updating expected dependencies. (#45992)

Keras expects keras_preprocessing 1.0.2 and 1.0.4. 1.0.3 and 1.0.5
are respectively in nixpkgs.

ZHF #45960

(cherry picked from commit e33be2a)

pkgs/development/python-modules/keras/default.nix

@@ -25,6 +25,14 @@ buildPythonPackage rec {
  keras-applications keras-preprocessing
  ];
 
+ # Keras 2.2.2 expects older versions of keras_applications
+ # and keras_preprocessing. These substitutions can be removed
+ # for for the next Keras release.
+ postPatch = ''
+ substituteInPlace setup.py --replace "keras_applications==1.0.4" "keras_applications==1.0.5"
+ substituteInPlace setup.py --replace "keras_preprocessing==1.0.2" "keras_preprocessing==1.0.3"
+ '';
+
  # Couldn't get tests working
  doCheck = false;