Traitlets

5.1.1 fixes compatibility issues with Python 3.10 (rc2).

is recommended for all users. What follow is a non-exhaustive list of
changes:

- Removal of the `ipython_genutils` dependency, this should remove
any direct and indirect reliance on `nose` and prepare traitlets
5.1 for Python 3.10 and above compatibility, some test suite
changes also accommodate Python 3.10 changes. If you package
traitlets downstream, make sure to remove this dependency.
- Removal of `ipython_genutils` may have change the default encoding
detected for the command line argument parsing when not utf-8. We
expect this to affect a small portion of older windows version. If
you encounter issue let us know.
- Stop recommendation of `CUnicode` in some circumstances as it's
deprecated.
- Our test suite is now using GitHub action instead of travis CI. If
you are packaging downstream using the git repository, you may
have to exclude the `.github` folder now, and can remove exclusion
of
- It fixes a parsing issue for list of one single element on the
CLI.
- We reserve the right to remove official support for Python 3.7 in
subsequent minor revisions.

- Support deprecated literals for sets, tuples on the command-line:
`nbconvert --TagRemovePreprocessor.remove_cell_tags='{"tag"}'`
- Fix `from_string_list` for Tuples in general
- Fix support for `List(default_value=None, allow_none=True)` and
other Container traits
- Fix help output for nested aliases and tuple traits

- Support deprecated use of byte-literals for bytes on the
command-line: `ipython kernel --Session.key="b'abc'"`. The
`b` prefix is no longer needed in traitlets 5.0, but is
supported for backward-compatibility
- Improve output of configuration errors, especially when help output
would make it hard to find the helpful error message

- Fix regression in handling `--opt=None` on the CLI for
configurable traits with `allow_none=True`