Update appveyor.yml

appveyor.yml

@@ -19,6 +19,8 @@ install:
   - cmd: call %PYTHON%
   - cmd: conda config --set always_yes yes --set changeps1 no
   - cmd: conda update -q conda
+  - cmd: conda create -q -n test python=$PYTHON_VERSION
+  - cmd: source activate test
   - cmd: conda config --add channels conda-forge
   - cmd: conda install -c conda-forge pvl protobuf gdal numpy pandas sqlalchemy pyyaml networkx affine h5py scipy
   - cmd: conda install conda-build anaconda-client pytest-cov
@@ -33,5 +35,6 @@ test_script:
   - cmd: pytest plio/
 
 on_success:
+  - cmd: source deactivate
   - cmd: conda config --set anaconda_upload yes
   - cmd: conda build --token %CONDA_UPLOAD_TOKEN% .