Replace httpx and httpx-sse with httpx2 #3473

Job	Run time
checks / readme-snippets	16s
checks / docs	37s
checks / pre-commit	54s
checks / test (3.12, locked, windows-latest)	1m 58s
checks / test (3.11, lowest-direct, windows-latest)	1m 54s
checks / test (3.10, locked, windows-latest)	1m 56s
checks / test (3.10, lowest-direct, windows-latest)	1m 54s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 21s
checks / test (3.11, locked, ubuntu-latest)	1m 26s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 28s
checks / test (3.13, lowest-direct, windows-latest)	1m 57s
checks / test (3.12, locked, ubuntu-latest)	1m 33s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 31s
checks / test (3.11, locked, windows-latest)	1m 54s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 25s
checks / test (3.10, locked, ubuntu-latest)	1m 32s
checks / test (3.12, lowest-direct, windows-latest)	1m 57s
checks / test (3.14, locked, windows-latest)	2m 0s
checks / test (3.14, locked, ubuntu-latest)	1m 22s
checks / test (3.14, lowest-direct, windows-latest)	1m 55s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 28s
checks / test (3.13, locked, ubuntu-latest)	1m 16s
checks / test (3.13, locked, windows-latest)	1m 51s
all-green	4s
	35m 29s

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