try fix pyenv path

.azure-pipelines/templates/steps/tox-steps.yml

@@ -27,6 +27,8 @@ steps:
   - bash: |
       set -e
       curl https://pyenv.run | bash
+      export PYENV_ROOT="$HOME/.pyenv"
+      command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"
       eval "$(pyenv init -)"
       pyenv install ${PYTHON_VERSION}
       pyenv shell ${PYTHON_VERSION}