fix AttributeError thrown by str.removeprefix when python < 3.9

[shtlrs]

Closes #252

Sorry for that, I forgot about the python 3.8 support.

[supakeen]

Thanks, interesting CI failures on this PR. Expected?

[shtlrs]

It's due to where the patch is being made I think.

I know that patching has this kinds of gotchas however I'm using pytest's monkeypatch and rn idk really know why it's happening.

I'll have a proper look later on.

[shtlrs]

@supakeen It's fixed now.

I think the problem lies within the design of the provider class.

During the test runtime/startup time, the get_config could be called by some test, so the _config cls isntance is set, which mean s that it has already loaded the environment before the patching happens, and thus, all subsequent calls will use that class instance instead of making a fresh one & loading the patched env.

I opted for instantiation Configuration directly here since we're only testing something "trivial" and there's no application logic.

[supakeen]

Thanks yea, we can probably fix that issue when it's used by multiple tests and it becomes a chore.