feat: added Graph.Prufer(), closes #750 #1485

Job	Run time
Build sdist and test extra dependencies	2m 46s
Build wheels on Linux (x86_64)	15m 38s
Build wheels on Linux (aarch64/manylinux)	0s
Build wheels on Linux (i686)	13m 54s
Build wheels on Linux (aarch64/musllinux)	0s
Build wheels on macOS (x86_64)	24m 57s
Build wheels for WebAssembly	4m 48s
Build wheels on macOS (arm64)	9m 16s
Build with sanitizers for debugging purposes	49s
Build wheels on Windows (Win32)	12m 47s
Build wheels on Windows (x64)	29m 19s
	1h 54m 14s

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