scikit-hep/hist: Version 2.5.0

Stacks support axes, math operations, projection, setting items, and iter/dict construction. They also support histogram titles in legends. Added histoprint support for Stacks. #291 #315 #317 #318 Added name= and label= to histograms, include Hist arguments in QuickConstruct. #297 AxesTuple now supports bulk name setting, h.axes.name = ("a", "b", ...). #288 Added hist.new alias for hist.Hist.new. #296 Added "efficiency" uncertainty_type option for ratio_plot API. #266 #278 Smaller features or fixes: Dropped Python 3.6 support. #194 Uses boost*histogram 1.2.x series, includes all features and fixes, and Python 3.10 support. No longer require scipy or iminuit unless actually needed. #316 Improve and clarify treatment of confidence intervals in intervals submodule. #281 Use NumPy 1.21 for static typing. #285 Support running tests without plotting requirements. #32