Port mtcnn to Tensorflow 2

Using the TF1 model.pb

conda/meta.yaml

@@ -41,7 +41,7 @@ requirements:
     - numpy {{ numpy }}
     - scipy {{ scipy }}
     - matplotlib {{ matplotlib }}
-    - tensorflow {{ tensorflow }}
+    - tensorflow {{ tensorflow }}  # [linux]
   run:
     - python
     - setuptools
@@ -51,7 +51,7 @@ requirements:
     - {{ pin_compatible('numpy') }}
   run_constrained:
     - {{ pin_compatible('matplotlib') }}
-    - {{ pin_compatible('tensorflow') }}
+    - {{ pin_compatible('tensorflow') }}  # [linux]
 
 test:
   imports:
@@ -78,7 +78,7 @@ test:
     - sphinx
     - sphinx_rtd_theme
     - matplotlib
-    - tensorflow
+    - tensorflow  # [linux]
 
 about:
   home: https://www.idiap.ch/software/bob/