Add hostname to json output of benchmarks
We are currently posting benchmarking results to elasticsearch (!74 (merged)). Because benchmark results depend on the configuration of the machine where they are run, it is important to be able to discern in which environment each set of tests was run. Pytest-benchmark already has a machine uid included in the resulting json, but if the tests are run inside a docker container then the machine id will be the same regardless of in which host the container is running.
We have to add the host hostname to the json output of benchmarks. This work can also be interesting if it paves the way for adding more metrics as memory and cpu usage of each test, and even custom metrics (as reactor responsiveness). We should talk to pytest-benchmark upstream (https://github.com/ionelmc) and see if he has ideas and is interested in having this kind of code included in pytest-benchmark.