Release 2.9.0

Changes from 2.8.0 to 2.9.0

• Dynamic plugins as Python wheels are supported now!
  This new feature allows for creating plugins in C, distribute
  them as wheels, and load them dynamically in runtime.
  Small example at https://github.com/Blosc/blosc2_plugin_example

• BloscLZ can achieve more speed in clevel 1 now.

• Internal Zstd sources updated to latest 1.5.5 version.

• Copyright notice updated. Thanks to @DimitriPapadopoulos.