paraview: specify Python 2 for build

projects/paraview.cmake

@@ -157,6 +157,7 @@ superbuild_add_project(paraview
     -DPARAVIEW_ENABLE_QT_SUPPORT:BOOL=${qt5_enabled}
     -DPARAVIEW_ENABLE_FFMPEG:BOOL=${ffmpeg_enabled}
     -DPARAVIEW_ENABLE_PYTHON:BOOL=${PARAVIEW_ENABLE_PYTHON}
+    -DPARAVIEW_PYTHON_VERSION:STRING=2
     -DPARAVIEW_ENABLE_COSMOTOOLS:BOOL=${cosmotools_enabled}
     -DPARAVIEW_ENABLE_XDMF3:BOOL=${xdmf3_enabled}
     -DPARAVIEW_ENABLE_LAS:BOOL=${las_enabled}