Release of PyMuPDF-1.20.0

[julian-smith-artifex-com]

PyMuPDF-1.20.0 has been released.

Wheels for Windows, Linux and MacOS, are available on pypi.org and can be installed in the usual way, for example:

pip install --upgrade pymupdf

This release integrates the recently-released MuPDF-1.20.0, and has fixes for #1733 and #1738. The latter also contains an additional fix for occasional SEGVs when freeing documents.

Building from source works slightly differently from before:

• We now automatically download the required MuPDF source and build it into PyMuPDF.
• Python sdists (source distributions) already contain the required MuPDF source and build without downloading.
• One can override the default build behaviour by setting environmental variables, for example to build with a system-installed mupdf. See the doc-comment at the start of setup.py for details.