Use a venv for the build.

Author: rcurtin

Jenkinsfile

@@ -19,6 +19,10 @@ pipeline
       steps
       {
         sh '''
+          python3 -m venv venv/
+          source venv/bin/activate
+          pip3 install numpy pandas cython setuptools twine cibuildwheel
+
           git clone https://github.com/mlpack/mlpack
           cd mlpack/
           git checkout $MLPACK_VERSION
@@ -124,6 +128,7 @@ pipeline
 
               sh '''
                 echo "CIBW_BUILD: $CIBW_BUILD"
+                source venv/bin/activate
                 cibuildwheel --output-dir wheelhouse mlpack/build/src/mlpack/bindings/python/
               '''
             }
@@ -135,6 +140,7 @@ pipeline
                 archiveArtifacts 'wheelhouse/*.whl'
 
                 sh '''
+                  source venv/bin/activate
                   echo "[pypi]" > ~/.pypirc
                   echo "username = __token__" >> ~/.pypirc
                   echo "password = $TWINE_PYPI_TOKEN" >> ~/.pypirc