feat: boost-histogram 1.0 compatibility and typing updates

[alexander-held]

This enables support for boost-histogram>=1.0.0. Subclassing Histogram requires a family keyword argument (optional starting with boost-histogram 1.0.1), and the boost-histogram library is now typed.

resolves #201

Overview of changes

* support and require boost-histogram>=1.0.0
* improved type checking via pre-commit
* added test for histogram properties
* skip mypy in CI for Python 3.7

Typing changes

For reading yields and variances, switch to using h.values() and h.variances() instead of h.view().value and h.view().variance. The view()-based method is still used for writing yields / variances directly.

Calling numpy functions with values/variances requires a # type: ignore, as does setting values via view().
See scikit-hep/boost-histogram#527 and scikit-hep/boost-histogram#525 (comment)). Some of these # type: ignore may possibly be removed in the future with boost-histogram updates.

The typing revealed a small typing bug in cabinetry.route, which will be resolved in a separate PR (here only temporarily fixed via # type: ignore).

CI / pre-commit updates

The CI is updated to skip mypy with Python 3.7, since the boost-histogram syntax requires at least Python 3.8 (see scikit-hep/boost-histogram#525 (comment)).

For type checking, the requirement is boost-histogram>=1.0.1 due to scikit-hep/boost-histogram#525 (comment). The pre-commit version requirement is set accordingly. boost-histogram 1.0.0 will fail with mypy due to two typing bugs (ellipsis/constructor), see also 1.0.1 changelog.

To get mypy working correctly in pre-commit, also adding boost-histogram to the environment requirements (and adding typed numpy at the same time).

Other notes

Also adding a test for Histogram properties.

[codecov]

Codecov Report

Merging #204 (35a0e14) into master (2911813) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #204   +/-   ##
=======================================
  Coverage   98.25%   98.25%           
=======================================
  Files          15       15           
  Lines        1716     1717    +1     
  Branches      267      267           
=======================================
+ Hits         1686     1687    +1     
  Misses         28       28           
  Partials        2        2           

Impacted Files	Coverage Δ
src/cabinetry/contrib/histogram_creation.py	100.00% <100.00%> (ø)
src/cabinetry/histo.py	100.00% <100.00%> (ø)
src/cabinetry/route.py	100.00% <100.00%> (ø)

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