bpython: updated to 0.23

0.23
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General information:

* More and more type annotations have been added to the bpython code base.
* Some work has been performed to stop relying on blessings.

New features:

* Auto-closing brackets option added. To enable, add `brackets_completion = True` in the bpython config
  Thanks to samuelgregorovic

Fixes:

* Improve handling of SyntaxErrors
* Fix crash on Ctrl-Z
* Fix tests for Python 3.10.1 and newer
* Handle optional `readline` parameters in `stdin` emulation
* Fix handling of `__name__`
* Fix function signature completion for `classmethod`s

Changes to dependencies:

* curtsies 0.4 or newer is now required

Support for Python 3.6 has been dropped.

(adam)