fix(auth): strip trailing slashes from OAuth metadata URLs #3155

Job	Run time
checks / readme-snippets	14s
checks / pre-commit	56s
checks / docs	41s
checks / test (3.11, lowest-direct, windows-latest)	1m 46s
checks / test (3.10, lowest-direct, windows-latest)	1m 37s
checks / test (3.12, locked, windows-latest)	1m 31s
checks / test (3.14, lowest-direct, ubuntu-latest)	52s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 0s
checks / test (3.13, lowest-direct, ubuntu-latest)	56s
checks / test (3.10, locked, ubuntu-latest)	56s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 1s
checks / test (3.13, locked, windows-latest)	1m 24s
checks / test (3.13, lowest-direct, windows-latest)	1m 36s
checks / test (3.13, locked, ubuntu-latest)	58s
checks / test (3.11, locked, ubuntu-latest)	55s
checks / test (3.12, lowest-direct, windows-latest)	1m 41s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 2s
checks / test (3.14, lowest-direct, windows-latest)	1m 45s
checks / test (3.12, locked, ubuntu-latest)	1m 23s
checks / test (3.11, locked, windows-latest)	1m 31s
checks / test (3.10, locked, windows-latest)	1m 29s
checks / test (3.14, locked, windows-latest)	2m 20s
checks / test (3.14, locked, ubuntu-latest)	2m 3s
all-green	3s
	29m 40s

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