Pin setuptools to 68.0.0 to fix Ray 2.7.0 compatibility

[ShakirKhurshid]

Problem

When following the course setup instructions, ray.data.read_csv(DATASET_LOC) fails with:

ModuleNotFoundError: No module named 'pkg_resources._vendor'

This occurs because Ray 2.7.0 expects older internal APIs from setuptools that were removed in setuptools 70+.

Solution

Pin setuptools to version 68.0.0, which is compatible with Ray 2.7.0 and maintains the expected API structure.

Testing

• Verified that ray.data.read_csv() works correctly with this pinned version
• Tested with Python 3.10.11 as specified in course setup

Impact

This fix ensures the course environment works out-of-the-box for new learners without requiring them to debug dependency issues.
Fixes issue #274