Fix filename for image in manual that doesn't show. #869

Job	Run time
Test in Docker container	21m 58s
Test with Python (3.9, ubuntu-latest)	23m 42s
Calculate and upload test coverage	29m 34s
Test with Python (3.9, macOS-latest)	20m 45s
Test with Python (3.9, windows-latest)	17m 49s
Test with Python (3.10, ubuntu-latest)	23m 19s
Test with Python (3.10, macOS-latest)	21m 35s
Test with Python (3.10, windows-latest)	18m 21s
Test with Python (3.11, ubuntu-latest)	23m 24s
Test with Python (3.11, macOS-latest)	19m 13s
Test with Python (3.11, windows-latest)	18m 10s
Test with Python (3.12, ubuntu-latest)	23m 30s
Test with Python (3.12, macOS-latest)	20m 6s
Test with Python (3.12, windows-latest)	19m 38s
	5h 1m 4s

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