Supported Python versions 3.3 to 3.13

[kieran-ryan]

🤔 What's changed?

• Added Python 3.13 support
• Fixed support for Python 3.3
• Dropped support for Python 2
• Enabled mando 0.8.x installations
• Added notebook extra install (pip install radon[notebook])
• Added missing toml extra install to poetry build

⚡️ What's your motivation?

• Officially support the latest stable release of Python (3.13)
• Reinstate support for Python 3.3 - impacted with attempted installation of an incompatible colorama distribution since v4.2.0 (Adapt dependency on colorama according to python version #195)
• Dropped support for incompatible Python 2 - since v6.0.0, following removal of futures dependency (chore: remove obsolete future dep #234) and incompatibilities with pyproject.toml support code (pyproject.toml support #236) - improving project maintainability and aligning with mando dropping Python 2 support in v0.8.0 (drop python2 support, six mando#57)
• Simplify notebook support installation and protect for possible changes to underlying dependencies
• Closes Please add support for mando 0.8* #268 - dropping installation of Python 2 dependencies with latest releases
• Closes README: Correct Python version compatibility #259

Python 2 incompatibility

$ python2.7 -m radon cc project/
Traceback (most recent call last):
  File "/home/codespace/.pyenv/versions/2.7.18/lib/python2.7/runpy.py", line 174, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/home/codespace/.pyenv/versions/2.7.18/lib/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/workspaces/radon/radon/__main__.py", line 4, in <module>
    main()
  File "radon/__init__.py", line 10, in main
    from radon.cli import program, log_error
  File "radon/cli/__init__.py", line 23, in <module>
    from radon.cli.harvest import (
  File "radon/cli/harvest.py", line 6, in <module>
    from builtins import super
ImportError: No module named builtins

This can be resolved by installing futures.

python2.7 -m pip install futures

However an additional error is encountered within configuration parsing.

$ python2.7 -m radon cc project/
Traceback (most recent call last):
  File "/home/codespace/.pyenv/versions/2.7.18/lib/python2.7/runpy.py", line 174, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/home/codespace/.pyenv/versions/2.7.18/lib/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/workspaces/radon/radon/__main__.py", line 4, in <module>
    main()
  File "radon/__init__.py", line 10, in main
    from radon.cli import program, log_error
  File "radon/cli/__init__.py", line 98, in <module>
    _cfg = FileConfig()
  File "radon/cli/__init__.py", line 45, in __init__
    self.file_cfg = self.file_config()
  File "radon/cli/__init__.py", line 85, in file_config
    config.read_dict(FileConfig.toml_config())
AttributeError: RawConfigParser instance has no attribute 'read_dict'

Code optimisations have been largely applied by the ruff linter through its --fix functionality; using the pyupgrade (UP) ruleset.

Python 3.3 incompatibility

Package installation fails with Python 3.3 as installation of an incompatible distribution of colorama is attempted which is only supported from Python 3.4.

py -3.3 -m pip install radon
DEPRECATION: Python 3.3 supported has been deprecated and support for it will be dropped in the future. Please upgrade your Python.
Collecting radon
  Downloading https://files.pythonhosted.org/packages/93/f7/d00d9b4a0313a6be3a3e0818e6375e15da6d7076f4ae47d1324e7ca986a1/radon-6.0.1-py2.py3-none-any.whl (52kB)
    100% |################################| 61kB 596kB/s
Collecting mando<0.8,>=0.6 (from radon)
  Downloading https://files.pythonhosted.org/packages/d2/f0/834e479e47e499b6478e807fb57b31cc2db696c4db30557bb6f5aea4a90b/mando-0.7.1-py2.py3-none-any.whl
Collecting colorama==0.4.1; python_version <= "3.4" (from radon)
  Downloading https://files.pythonhosted.org/packages/4f/a6/728666f39bfff1719fc94c481890b2106837da9318031f71a8424b662e12/colorama-0.4.1-py2.py3-none-any.whl
colorama requires Python '>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*' but the running Python is 3.3.5

🏷️ What kind of change is this?

• 💥 Breaking change (incompatible changes to the API) - although the breaking change (dropping Python 2 support) itself occurred with v6.0.0

♻️ Anything particular you want feedback on?

• Whether earlier Python 3 versions could be dropped; and if so whether should be part of this pull request or a follow up
• Whether additional code optimisations could be applied following the removal of Python 2
• Whether to split any commits into separate pull requests
• Whether an encoding keyword argument can be provided with open in PyPy