Implementation name "python" is hard-coded in test_venv

Bug report

Bug description:

The behavior of venv was changed in 48d926269963.
Before this change, libpath was hard-coded as python%d.%d. It has now been replaced with sysconfig.get_path(..., scheme='venv').

However, while this patch was applied, the corresponding test, test_venv was not updated and was left unchanged. As a result, test_venv now fails when sysconfig is overridden.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-143000

从 test_venv 测试开始，检查提交 48d926269963 中的 venv 更改，尤其是 sysconfig 的覆盖行为。更新测试的预期实现名称，使其反映当前的 venv 路径查找，然后运行 test_venv，并确认在覆盖 sysconfig 时测试通过。