Compatibility with newer Python versions

[rpatureau]

Installing with Python >= 3.10 is not possible "out-of-the-box"
It seems there is an issue with PyYAML not being compatible with Cython >= 3

Installing PyYAML 6.0.1 instead solves the issue (tested with a fresh install of Python 3.10.14 and Python 3.12.3)

PyYAML changes:

6.0.1 (2023-07-18)

• Pin Cython build constraint to < 3.0 yaml/pyyaml#702 -- pin Cython build dep to < 3.0

6.0 (2021-10-13)

• Change README format to Markdown yaml/pyyaml#327 -- Change README format to Markdown
• Add a test for YAML 1.1 types yaml/pyyaml#483 -- Add a test for YAML 1.1 types
• Fix yaml11 float resolver for '.' yaml/pyyaml#497 -- fix float resolver to ignore . and ._
• Drop 2.7 support yaml/pyyaml#550 -- drop Python 2.7
• Fix spelling of “hexadecimal” yaml/pyyaml#553 -- Fix spelling of “hexadecimal”
• Fix issue with representing Enum types yaml/pyyaml#556 -- fix representation of Enum subclasses
• Fix warning errors of the libyaml binding yaml/pyyaml#557 -- fix libyaml extension compiler warnings
• Use with statements to eliminate ResourceWarnings yaml/pyyaml#560 -- fix ResourceWarning on leaked file descriptors
• yaml.load(s, Loader=...) requires Loader= argument always yaml/pyyaml#561 -- always require Loader arg to yaml.load()
• Various setup fixes yaml/pyyaml#564 -- remove remaining direct distutils usage

[rpatureau]

Successfully tested with Python 3.8.19