Fix typo and simplify boolean assignment in setup.py

[Prer26]

Summary

This PR makes small improvements to the setup.py build script by fixing a typo and simplifying a boolean assignment.

Changes

• Corrected a typo in a comment (sptring → string)
• Simplified the is_CI_build assignment using a direct boolean expression

Why this change

• Improves code readability and consistency with Python best practices
• Reduces unnecessary conditional verbosity without altering behavior

Impact

• No functional changes
• No effect on build or runtime behavior
• Purely a readability and maintainability improvement