pygobject ships no PyPI wheels, so pip install always compiles it from
source, which requires the OS gobject-introspection dev package at
install time. As a mandatory dependency this broke plain `pip install
csaxs_bec` on CI and on Read the Docs, neither of which has that
package installed. Move it to the `allied_vision` extra so only hosts
that actually run the camera (which already need Aravis + the OS
package present) opt in via `pip install csaxs_bec[allied_vision]`.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
