Update contributor guide for JB2 #383

Job	Run time
ubuntu-latest with Python 3.14 and developer versioned dependencies	1m 51s
windows-latest with Python 3.13	2m 16s
ubuntu-latest with Python 3.13	1m 25s
ubuntu-latest with Python 3.10 and oldest versioned dependencies	1m 40s
ubuntu-latest with Python 3.12 and latest or pre-release version of dependencies	1m 27s
ubuntu-latest with Python 3.11 and latest released version of dependencies	1m 24s
macos-latest with Python 3.13	1m 43s
	11m 46s

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