Build 56

Linux x86_64 release of Marker (egui + MuPDF).

Commit: a3ecc9e8a15bf53e43ea4b74a285216b46fe0330

Runtime shared libraries typically needed on the host:
fontconfig, freetype, brotli, jbig2dec, lcms2, libjpeg, openjpeg2, zlib.

License: MIT.

Full Changelog: build-54...build-56