Update build_win.cmd

Author: Coderx7

scripts/build_win.cmd

@@ -39,11 +39,11 @@ if DEFINED APPVEYOR (
     !PYTHON_EXE! --version
     :: Add the required channels
     conda config --add channels conda-forge
-    :: conda config --add channels willyd
+    conda config --add channels willyd
     :: Update conda
     conda update conda -y
     :: Download other required packages
-    conda install --yes cmake ninja numpy scipy protobuf six scikit-image pyyaml pydotplus graphviz
+    conda install --yes cmake ninja numpy scipy protobuf==3.1.0 six scikit-image pyyaml pydotplus graphviz
 
     if ERRORLEVEL 1  (
       echo ERROR: Conda update or install failed