Removing warnings filter changes from package

[further-reading]

The code warnings.simplefilter("default") expands what warnings are shown and can cause warnings and errors which are normally not expected in other packages to show. In addition, depending on the import order this can override changes to the warnings filter made by the user. I think it would be better to remove this from the package to prevent issues caused by users receiving unexpected warnings/errors.

[adamjstewart]

Thanks for the PR! I think you're probably right, we don't want to change the global warnings settings for all applications. Unfortunately that means that the warnings won't be raised by default and users will likely only notice this when running something like pytest. I can just keep it deprecated for longer in that case.

I'm not sure if this warrants an entirely new release? I might wait for other features or bugfixes before cutting a new release.