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Make `auth` in `GitHubApiDetails` optional #4921

Job	Run time
Rust analysis (ubuntu-latest, stable-v2.20.7)	1m 23s
Rust analysis (ubuntu-latest, linked)	1m 46s
Rust analysis (ubuntu-latest, default)	1m 46s
Rust analysis (ubuntu-latest, nightly-latest)	1m 47s
Rust analysis (ubuntu-latest, stable-v2.22.1)	1m 56s
	8m 38s