Jupyter-core

the fix below for the Windows tests. Unfortunately, the 4.8.1 release
commit and tag were not pushed to GitHub. We are releasing 4.8.2 so we
have a commit and tag in version control.

- Fix windows test regression ([240](https://github.com/jupyter/jupyter_core/pull/240))

[on GitHub](https://github.com/jupyter/jupyter_core/releases/tag/4.8.0)

See the [jupyter_core
4.8](https://github.com/jupyter/jupyter_core/milestone/20?closed=1)
milestone on GitHub for the full list of pull requests and issues
closed.

jupyter-core now has experimental support for PyPy (Python 3.7). Some
features are known not to work due to limitations in PyPy, such as
hidden file detection on Windows.

- Print an error message instead of an exception when a command is not
found ([218](https://github.com/jupyter/jupyter_core/pull/218))
- Return canonical path when using `%APPDATA%` on Windows
([222](https://github.com/jupyter/jupyter_core/pull/222))
- Print full usage on missing or invalid commands
([225](https://github.com/jupyter/jupyter_core/pull/225))
- Remove dependency on `pywin32` package on PyPy
([230](https://github.com/jupyter/jupyter_core/pull/230))
- Update packages listed in `jupyter --version`
([232](https://github.com/jupyter/jupyter_core/pull/232))
- Inherit base aliases/flags from traitlets Application, including
`--show-config` from traitlets 5 ([233](https://github.com/jupyter/jupyter_core/pull/233))
- Trigger warning when trying to check hidden file status on PyPy
([238](https://github.com/jupyter/jupyter_core/pull/238))

[on GitHub](https://github.com/jupyter/jupyter_core/releases/tag/4.7.1)

- Allow creating user to delete secure file ([213](https://github.com/jupyter/jupyter_core/pull/213))

[on GitHub](https://github.com/jupyter/jupyter_core/releases/tag/4.7.0)

See the [jupyter_core
4.7](https://github.com/jupyter/jupyter_core/milestone/19?closed=1)
milestone on GitHub for the full list of pull requests and issues
closed.

- Add a new `JUPYTER_PREFER_ENV_PATH` variable, which can be set to
switch the order of the environment-level path and the user-level
path in the Jupyter path hierarchy (e.g., `jupyter --paths`). It is
considered set if it is a value that is not one of 'no', 'n',
'off', 'false', '0', or '0.0' (case insensitive). If you are
running Jupyter in multiple virtual environments as the same user,
you will likely want to set this environment variable.
- Drop Python 2.x and 3.5 support, as they have reached end of life.
- Add Python 3.9 builds to testing, and expand testing to cover
Windows, macOS, and Linux platforms.
- `jupyter --paths --debug` now explains the environment variables
that affect the current path list.
- Update the file hidden check on Windows to use new Python features
rather than ctypes directly.
- Add conda environment information in `jupyter troubleshoot`.
- Update `_version.version_info` and `_version.__version__` to follow
Python conventions.