Use full python version in `pyvenv.cfg` (#1979)
## Summary
For a venv created by `virtualenv`, the `pyvenv.cfg` file specifies the
full version string in the `version_info` field:
```
home = /Users/x/.rye/py/cpython@3.12.1/install/bin
implementation = CPython
version_info = 3.12.1.final.0
virtualenv = 20.25.0
include-system-site-packages = false
base-prefix = /Users/x/.rye/py/cpython@3.12.1/install
base-exec-prefix = /Users/x/.rye/py/cpython@3.12.1/install
base-executable = /Users/x/.rye/py/cpython@3.12.1/install/bin/python3
```
The relevant code can be found here:
https://github.com/pypa/virtualenv/blob/4ca8a20c179a03e649ce696a0df3e6e3344a18c9/src/virtualenv/create/creator.py#L167
This PR changes `pyvenv.cfg` created by uv for better compatibility with
`virtualenv`.
## Test Plan
```sh
uv venv
cat .venv/pyvenv.cfg
```
