v0.9.1

Changed

• info["nclx_profile"] changed type from bytes(format of which was not described) to dict.
• Drop support for Python 3.6, PyPy 3.7. Added PyPy 3.9 wheels.
• convert_to method: RGBa to RGB mode support was removed(last Pillow supports it). #67

Fixed

• Small memory leak when opening image with nclx color profile. #64