🤖 ci: add workflow to measure test runtime #53

Description

CI workflow that records how long the test suite takes to run (each test). This will provide useful insights into the efficiency of the test setup and how changes to the object mother pattern implementation may affect performance over time.

Why this is useful

• It gives measurable feedback on whether the usage of the object mother pattern improves or degrades test performance.
• It helps catch performance regressions early.
• It aids in optimization decisions, especially when scaling test coverage.