Make sure you have a locale which supports ``UTF-8``.
If you are in a minimal environment (such as a docker container), the locale may be something minimal like ``POSIX``.
We test with the following settings.
However, it should be fine if you're using a different UTF-8 supported locale.

.. code-block:: console

   $ locale  # check for UTF-8

   $ sudo apt update && sudo apt install locales
   $ sudo locale-gen en_US en_US.UTF-8
   $ sudo update-locale LC_ALL=en_US.UTF-8 LANG=en_US.UTF-8
   $ export LANG=en_US.UTF-8

   $ locale  # verify settings