MGT-python 1.9.2

Added

• musicalgestures.__version__. The package exposed no version attribute
  at all, so code could only learn the version through the installed
  metadata, and a script run against a source checkout could not learn it
  at all.

Fixed

• The version has one source. pyproject.toml reads
  musicalgestures.__version__ through a dynamic version rather than
  carrying its own copy, so adding the attribute did not create a second
  number to drift. That drift is not hypothetical across these toolboxes:
  ambiscape shipped three releases reporting a version other than their
  own and musiscape shipped one, in both cases because a bump edited
  pyproject.toml alone. tests/test_version.py fails if a static
  version reappears there, if the build stops reading the module
  attribute, or if the two numbers diverge.