py-imageio: updated to 2.9.0

2.9.0:

Fixed
More robust loading of FEI SEM data.
Fix webcam not working on Win10.

Added
Add a few standard images useful to 3D visualization.
The timeout used in HTTP requests can now be set with an environment variable.
The DICOM plugin can now used gdcm for compressed transfer formats.
Better support for itk/sitk plugins.
Test coverage and CI for ARM.

(adam)