Appveyor/Windows: Add Cython to conda install (#1772)

Author: franzpoeschel

.appveyor.yml

@@ -86,7 +86,7 @@ install:
   - cmd: conda config --append channels conda-forge
 
   # Configure the VM.
-  - cmd: conda install -n root --quiet --yes numpy cmake hdf5 python=%CONDA_PY%
+  - cmd: conda install -n root --quiet --yes cython numpy cmake hdf5 python=%CONDA_PY%
   # ADIOS2 build only for 64bit Windows
   - cmd: if "%TARGET_ARCH%"=="x64" conda install -n root --quiet --yes adios2 python=%CONDA_PY%