Test timing issues for slow github test runners

[Charlesworth]

Some of the tests, in particular the eva_locker_test.py tests use sleeps to ensure thing happen within a set time frame. Unfortunately GitHub's free action test runners are slow enough that these tests can fail in a non-deterministic way if the runner is processing the test a bit slowly. As an example the following test run failed due to a timeout: https://github.com/automata-tech/eva_python_sdk/runs/831475589?check_suite_focus=true

To fix this issue either:

• increase to duration which is allowed for each test action in eva_locker_test.py (quick and easy but not ideal)
• remove any reliance on sleeps from eva_locker_test.py (this will be a longer task)

[LouisBrunner]

I think we should be able to mock any time component using libraries like this