Document supported Python versions in README

[StapeltonAriana]

Clarify that the client targets modern Python 3 versions (around 3.9+).
Suggest checking GitHub and PyPI releases when pinning a specific version or using older environments.

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Note

Clarifies supported Python versions (3.9+) with guidance on pinning/older envs and fixes the examples link formatting in README.

• README:
  • Clarify supported Python versions (tested on 3.9+) and advise checking GitHub/PyPI releases for pinning or older environments.
  • Fix formatting of the [/example](/examples) link.

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