fix(auth): strip trailing slashes from OAuth metadata URLs #3460

Job	Run time
checks / pre-commit	57s
checks / readme-snippets	16s
checks / docs	42s
checks / test (3.11, lowest-direct, windows-latest)	1m 50s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 23s
checks / test (3.11, locked, ubuntu-latest)	1m 24s
checks / test (3.11, locked, windows-latest)	1m 53s
checks / test (3.10, lowest-direct, windows-latest)	1m 59s
checks / test (3.10, locked, windows-latest)	2m 2s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 29s
checks / test (3.10, locked, ubuntu-latest)	1m 28s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 19s
checks / test (3.13, lowest-direct, windows-latest)	1m 57s
checks / test (3.12, locked, ubuntu-latest)	1m 35s
checks / test (3.12, locked, windows-latest)	1m 57s
checks / test (3.14, lowest-direct, windows-latest)	2m 3s
checks / test (3.13, locked, windows-latest)	1m 46s
checks / test (3.14, locked, windows-latest)	2m 14s
checks / test (3.13, locked, ubuntu-latest)	1m 13s
checks / test (3.12, lowest-direct, windows-latest)	1m 53s
checks / test (3.14, locked, ubuntu-latest)	1m 18s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 22s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 21s
all-green	2s
	35m 23s

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