matplotlib deprecation warning in plot()

[bfirsh]

Getting this warning in tests:

tests/test_plot.py::test_num_plots
  /Users/ben/p/keepsake/python/keepsake/experiment.py:446: MatplotlibDeprecationWarning: Adding an axes using the same arguments as a previous axes currently reuses the earlier instance.  In a future version, a new instance will always be created and returned.  Meanwhile, this warning can be suppressed, and the future behavior ensured, by passing a unique label to each axes instance.
    plotted_label = plt.axes().yaxis.get_label().get_text() or metric

cc @enochkan :)

[enochkan]

@bfirsh i'll investigate :)

[enochkan]

Sorry busy week at work. Will work on this over the weekend 👍

[enochkan]

@bfirsh sorry for the delay. Issue is fixed in PR #570