Report test duration in CI

[ascillitoe]

To identify long-running tests during CI, it would be helpful for overly long-running tests to report their duration. This could be achieved by:

1. Add a timeout with pytest-timeout, so that tests that take longer than a certain (relatively generous) duration would simply be killed. Long-running tests would then be reported as failed.
2. Add a pytest hook to report duration after each test. Something like this.

As noted by @jklaise , with option 2. a minimum duration threshold would be required to avoid cluttering the output.

[jklaise]

Just for context, we should also do the command line argument --durations=50 (report the top 50 long running tests at the end of the test suite). The reason we're considering a hook (or use of a timeout) is to identify long running tests before the test suite has finished. This is required because our MacOS CI tests frequently time out and take almost 6h to run (compared to ~1h on other OSes).

[jk]

@ascillitoe I'm not @jklaise

[ascillitoe]

@ascillitoe I'm not @jklaise

Apologies!

[jklaise]

Closing as implemented in #849.