Dear yt users,

As was previously mentionned in yt 4.0.0's release notes, we're planning to drop
support for Python 3.6 in our next feature release (4.1.0). The change is set to
happen on the dev branch of yt not earlier than October the 20th, this year.
This means that if you wish to use our most recent features and bugfixes past this date, you'll
need to make sure you're running Python 3.7 or newer. Note that the
4.0.x series will retain compatibility with Python 3.6.

The exact method to upgrade your Python runtime depends on what tool(s) you used to
install Python or to manage your environments. In general, please lookup the
method that applies to your tools. Here is the documentation for some common
methods:

- using venv (see "--upgrade" flag) https://docs.python.org/3/library/venv.html
- using conda https://docs.conda.io/projects/conda/en/latest/user-guide/tasks/manage-python.html#updating-or-upgrading-python

In general, yt is primarily tested with the latest Python versions available, so
we recommend upgrading Python to the latest version available to you. 

There will be a reminder in two weeks from now.
Note that we're also planning to officially support Python 3.10 as soon as possible,
but likely not earlier than mid-October.

Have a great day,
Clément Robert, on behalf of the yt dev team