tests: avoid racy HTTP test ports #2426

Job	Run time
checks / pre-commit	19s
checks / readme-snippets	14s
checks / test (3.11, lowest-direct, ubuntu-latest)	59s
checks / test (3.11, locked, windows-latest)	1m 39s
checks / test (3.12, locked, windows-latest)	1m 31s
checks / test (3.11, locked, ubuntu-latest)	53s
checks / test (3.11, lowest-direct, windows-latest)	1m 30s
checks / test (3.10, lowest-direct, windows-latest)	1m 32s
checks / test (3.10, locked, windows-latest)	1m 47s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 0s
checks / test (3.10, lowest-direct, ubuntu-latest)	53s
checks / test (3.10, locked, ubuntu-latest)	55s
checks / test (3.14, locked, ubuntu-latest)	2m 2s
checks / test (3.13, locked, windows-latest)	2m 7s
checks / test (3.14, locked, windows-latest)	2m 14s
checks / test (3.12, lowest-direct, windows-latest)	1m 43s
checks / test (3.13, locked, ubuntu-latest)	56s
checks / test (3.14, lowest-direct, ubuntu-latest)	48s
checks / test (3.14, lowest-direct, windows-latest)	1m 37s
checks / test (3.13, lowest-direct, windows-latest)	2m 1s
checks / test (3.12, locked, ubuntu-latest)	55s
checks / test (3.13, lowest-direct, ubuntu-latest)	59s
all-green	5s
	28m 39s

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