ENH TST: consider using pytest-timeout

[bsipocz]

While we have the timeout arg/config for most modules, something things still stuck, therefore we should consider dealing with it on the test infra level e.g. with pytest-timeout.
I believe sunpy uses it, maybe @Cadair can share the tricks if any of them are required.

[Cadair]

I don't think we do much with it other than just default config.