replaces black/flake8 formatting/linting with ruff and ensures numpy 2.0 compatibility

[remrama]

This PR replaces Black formatting and flake8 linting with Ruff. In doing so, it ensures NumPy 2.0 compatibility (present and future). Both were discussed in #444.

Main changes:

• Replaced black/flake8 with ruff in pyproject.toml
• Replaced black GitHub Action with ruff GitHub action
• Replaced black with ruff in Contributing sections of docs.
• Ran ruff's linter and formatter (in case of minor deviations from black and flake8)
• Ran ruff's numpy 2.0 compatibility enforcer

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 98.54%. Comparing base (a3fa6fb) to head (2c580c3). Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #446   +/-   ##
=======================================
  Coverage   98.54%   98.54%           
=======================================
  Files          19       19           
  Lines        3360     3360           
  Branches      547      492   -55     
=======================================
  Hits         3311     3311           
  Misses         26       26           
  Partials       23       23           

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