scikit-hep/hist: Version 2.3.0

Add plot_ratio to the public API, which allows for making ratio plots between the histogram and either another histogram or a callable. #161 Add .profile to compute a (N-1)D profile histogram. #160 Support plot1d / plot on Histograms with a categorical axis. #174 Add frequentist coverage interval support in the intervals module. #176 Allow plot_pull to take a more generic callable or a string as a fitting function. Introduce an option to perform a likelihood fit. Write fit parameters\' values and uncertainties in the legend. #149 Add fit_fmt= to plot_pull to control display of fit params. #168 Support _kw arguments for setting each axis in plotting. #193 Cleaner IPython completion for Python 3.7+. #17