Python: Fix incorrect instructions in README

[sljeff]

Motivation and Context

The README incorrectly suggests that Python users need to switch to C#.

Description

fix typo

Contribution Checklist

• [x] The code builds clean without any errors or warnings
• [x] The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• [x] All unit tests pass, and I have added new tests where possible
• [x] I didn't break anyone :smile: