Your colleague runs Python 3.10, but you have 3.12 installed. Suddenly, their use of datetime.UTC (new in 3.11) works fine on your machine but fails in CI. A .python-version file eliminates this ambiguity.

In 2000, Python 2.0 was released, marking a significant milestone in the language's evolution. Python 2.0 introduced a number of important features, including:

3.11.4

Here's a brief history of major Python versions:

If you're having trouble getting a specific version to run, feel free to share: