Revert "attempt to use pyenv shell to set version."

This reverts commit 4abfbe3.

Author: theengineear

circle/setup.sh

@@ -19,7 +19,6 @@ for version in ${PLOTLY_PYTHON_VERSIONS[@]}; do
     # exporting this variable (in this scope) chooses the python version
     pyenv global ${version}
     pyenv local ${version}
-    pyenv shell ${version}
     echo "Using pyenv version $(pyenv version)"
 
     # install core requirements all versions need

circle/test.sh

@@ -19,7 +19,6 @@ for version in ${PLOTLY_PYTHON_VERSIONS[@]}; do
     # exporting this variable (in this scope) chooses the python version
     pyenv global ${version}
     pyenv local ${version}
-    pyenv shell ${version}
     echo "Using pyenv version $(pyenv version)"
 
     echo "python -c 'import sys; print(sys.version_info)' yields:"