fix(auth): strip trailing slashes from OAuth metadata URLs #3524

Job	Run time
checks / pre-commit	23s
checks / readme-snippets	12s
checks / docs	1m 1s
checks / test (3.14, locked, ubuntu-latest)	1m 23s
checks / test (3.10, lowest-direct, windows-latest)	1m 49s
checks / test (3.11, lowest-direct, windows-latest)	1m 50s
checks / test (3.10, locked, ubuntu-latest)	1m 3s
checks / test (3.12, locked, ubuntu-latest)	1m 32s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 29s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 32s
checks / test (3.10, locked, windows-latest)	1m 50s
checks / test (3.13, lowest-direct, windows-latest)	1m 58s
checks / test (3.11, locked, ubuntu-latest)	1m 20s
checks / test (3.13, locked, windows-latest)	1m 59s
checks / test (3.14, locked, windows-latest)	1m 54s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 25s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 17s
checks / test (3.12, locked, windows-latest)	1m 44s
checks / test (3.14, lowest-direct, windows-latest)	1m 49s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 13s
checks / test (3.11, locked, windows-latest)	1m 56s
checks / test (3.13, locked, ubuntu-latest)	1m 10s
checks / test (3.12, lowest-direct, windows-latest)	1m 58s
all-green	5s
	33m 52s

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