Document `redirect_uri` wire-format change in OAuth migration note (#… #2856

Job	Run time
checks / readme-snippets	10s
checks / pre-commit	38s
checks / test (3.10, locked, windows-latest)	1m 32s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 32s
checks / test (3.10, locked, ubuntu-latest)	1m 3s
checks / test (3.11, lowest-direct, windows-latest)	1m 41s
checks / test (3.10, lowest-direct, windows-latest)	1m 30s
checks / test (3.12, locked, windows-latest)	1m 47s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 20s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 13s
checks / test (3.12, lowest-direct, windows-latest)	1m 51s
checks / test (3.11, locked, windows-latest)	1m 56s
checks / test (3.12, locked, ubuntu-latest)	1m 2s
checks / test (3.14, lowest-direct, windows-latest)	1m 38s
checks / test (3.13, locked, ubuntu-latest)	53s
checks / test (3.13, locked, windows-latest)	1m 30s
checks / test (3.13, lowest-direct, windows-latest)	1m 48s
checks / test (3.11, locked, ubuntu-latest)	1m 2s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 33s
checks / test (3.14, locked, ubuntu-latest)	2m 0s
checks / test (3.14, locked, windows-latest)	2m 24s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 14s
all-green	2s
	31m 19s

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