feat: add Pint integration for unit conversions

[nsmith-]

Closes #262

Example usage:

import pint

from hepunits.pint import to_clhep

ureg = pint.UnitRegistry()
vacuum_impedance = (
    (1 * ureg.vacuum_permeability / ureg.vacuum_permittivity) ** 0.5
).to(ureg.ohm)
print(f"Vacuum impedance: {vacuum_impedance}")
print(f"In CLHEP units: {to_clhep(vacuum_impedance)}")

resulting in

Vacuum impedance: 376.73031341191023 ohm
In CLHEP units: 6.035885054680593e-14

[codecov-commenter]

Codecov Report

❌ Patch coverage is 86.95652% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 98.67%. Comparing base (6804332) to head (c2dbec1).

Files with missing lines	Patch %	Lines
src/hepunits/pint.py	86.95%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##              main     #273      +/-   ##
===========================================
- Coverage   100.00%   98.67%   -1.33%     
===========================================
  Files            6        7       +1     
  Lines          278      301      +23     
===========================================
+ Hits           278      297      +19     
- Misses           0        4       +4     

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[eduardo-rodrigues]

Many thanks 👍! I will review this properly tomorrow.

[eduardo-rodrigues]

This looks great. Many thanks.

I added a couple of examples of usage.

It will be useful to update the README with a subsection on "Conversions to/from Pint" (or alike) at the bottom so that people realise this new functionality exists. See if you have a nice example to add or else we follow it up in a new PR.

[nsmith-]

Ok I added a section to the README

[eduardo-rodrigues]

I already made a release, https://github.com/scikit-hep/hepunits/releases/tag/v2.4.0, in case you have use cases already for your work.

[nsmith-]

Thanks, I likely will be using it!