When parsing .python-version rsconnect-python should adapt the version constraint to UV behavior

[amol-]

In most cases the .python-version file will contain just a version number like "3.12".

This introduces two issues:

1. "3.12" is not a valid PEP440 version specification, while uv handles it, connect does not as it expects ==3.12
2. ==3.12 actually means ==3.12.0 as version numbers are 0 padded. But that's not the behaviour you get in UV, as uv will use any available patch version. So we should intend it as ==3.12.*.

Thus rsconnect-python when parsing .python-version should check if it's a valid version specifier ( https://packaging.python.org/en/latest/specifications/version-specifiers/#id5 ) and if none of the comparison operators is specified ( ~=, ==, !=, <=, >=, <, >) it should prefix it with ~= as it's the operator that matches default uv behaviour.