Make PyMuPDF always log to stderr #3476

Job	Run time
build-deb	18m 40s
Build and install a Dangerzone RPM on Fedora 39	23m 28s
macOS	2m 19s
Build and install a Dangerzone RPM on Fedora 40	18m 33s
windows	4m 56s
install-deb (ubuntu-20.04, ubuntu, 20.04)	2m 51s
install-deb (ubuntu-22.04, ubuntu, 22.04)	2m 45s
install-deb (ubuntu-23.10, ubuntu, 23.10)	2m 38s
install-deb (ubuntu-24.04, ubuntu, 24.04)	2m 1s
install-deb (debian-bullseye, debian, bullseye)	2m 21s
install-deb (debian-bookworm, debian, bookworm)	2m 15s
install-deb (debian-trixie, debian, trixie)	1m 59s
	1h 24m 46s

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