make tests tolerant to authlib 1.5.2 error messages (#18390)

authlib 1.5.2 now single-quotes error messages in the claims, causing
three tests to fail.

Replace the comparison with a regex that accepts both single or double
quotes.

This succeeds the tests with both authlib 1.5.1 and 1.5.2.

See https://github.com/NixOS/nixpkgs/pull/402797 for context.

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