Fix PDF build for Python 3.14 #456

Job	Run time
sync / sync	49s
check / Lint translations	39s
check / Build docs (latex)	9m 0s
check / Build docs (html)	8m 19s
check / Check for zero-width space characters	8s
check / Build docs (epub)	8m 56s
check / Build docs (pdf)	11m 13s
	39m 4s

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