test: add case for odd starting value in Collatz sequence

[titikshit]

Overview
Adds a missing test case for handling odd-number Collatz inputs.

Motivation
Odd starts (like 25) help surface an easy mistake: using / produces floats, which breaks the integer sequence.
Using // keeps the logic consistent.
This test highlights the issue, and I suggest recommending // in the implementation

Changes
Added test_odd_number_start to verify steps(25) == 23.

[BethanyG]

Hi @titikshit 👋🏽

This problem is a practice exercise that has been pulled from a common repository. The content and tests have been auto-generated. To add, alter, or propose a test, we ask that you open an issue in the forum under problem specifications, since that is where this change would go so that it benefits more than just the Python track.