Don't always import tensorflow of pytorch in TMVA_CNN_Classification.py

Don't import tensorflow of pytorch for feature detection
TMVA_CNN_Classification.py.

The C++ version of the tutorial also doesn't do it, and importing
TensorFlow can have bad consequences like symbol collisions with the
system OpenBLAS.

Author: guitargeek

tutorials/tmva/TMVA_CNN_Classification.py

@@ -27,36 +27,13 @@
 import os
 import importlib.util
 
-useKerasCNN = False
-
-if ROOT.gSystem.GetFromPipe("root-config --has-tmva-pymva") == "yes":
-    useKerasCNN = True
-
 opt = [1, 1, 1, 1, 1]
 useTMVACNN = opt[0] if len(opt) > 0  else False
-useKerasCNN = opt[1] if len(opt) > 1 else useKerasCNN
+useKerasCNN = opt[1] if len(opt) > 1 else False
 useTMVADNN = opt[2] if len(opt) > 2 else False
 useTMVABDT = opt[3] if len(opt) > 3 else False
 usePyTorchCNN = opt[4] if len(opt) > 4 else False
 
-if useKerasCNN:
-    import tensorflow
-
-# PyTorch has to be imported before ROOT to avoid crashes because of clashing
-# std::regexp symbols that are exported by cppyy.
-# See also: https://github.com/wlav/cppyy/issues/227
-torch_spec = importlib.util.find_spec("torch")
-if torch_spec is None:
-    usePyTorchCNN = False
-    print("TMVA_CNN_Classificaton","Skip using PyTorch since torch is not installed")
-else:
-    import torch
-
-
-import ROOT
-
-#switch off MT in OpenMP (BLAS)
-
 TMVA = ROOT.TMVA
 TFile = ROOT.TFile