Add new parameter python_versions in copier.yml

[h-chmeruk]

I noticed that for parameters related to Python versions, we create a new array with Python versions in several places. Later, this will require us to manually add new or remove old Python versions in each of these arrays.
To avoid this, we can add a new parameter that defines all available Python versions once and use it in all other parameters related to Python versions.

Changes proposed in this pull request:

• Added a new parameter called python_versions to copier.yml, which defines all Python versions valid for the project.
• The choices for the minimum_python_version parameter are now created from the new python_versions parameter.
• The parameter valid_python_versions now also uses the new parameter python_versions to define the array of all available Python versions.
• Adjusted the conftest.py file, since the Python versions are now stored with obligatory apostrophes ' ' as follows:
  "minimum_python_version": "'3.11'",

[ahms5]

really nice feature, thank you. I just have a few comments.

[ahms5]

maybe use " instead of ', be usually use ", even we dont have a strinkt rule. This might make the change in conftest.py obsolete.

[ahms5]

Suggested change

	"minimum_python_version": "'3.11'",
	"minimum_python_version": "3.11",

[ahms5]

really nice

[ahms5]

Suggested change

	- "'{{ v }}'"
	- {{ v }}

do we really need them?

[h-chmeruk]

Actually, yes. The entire implementation is a bit tricky, and I'm not sure I fully understand it, but here's what I noticed:

After defining default: ["3.9", "3.10", "3.11", "3.12", "3.13", "3.14"], YAML stores it as python_versions = ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']. As soon as we try to create choices for minimum_python_version from python_versions, each element of the python_versions array is taken separately and treated as a float value. Since it is treated as a float value, the zero in 3.10 is removed and the choice is displayed as 3.1. And even if we put the choices in quotes, they will only be displayed correctly in the questions, but as soon as we select the choice with 3.10, it will be stored as a float, i.e. as 3.1. For this reason, we need to store the values as strings and not as floats...

But I've already noticed that I can just change the parameter type from yaml to str, so we only need a pair of quotation marks (to display the choices correctly).

[ahms5]

nice