Handle connection errors in StreamableHTTP post_writer #1416

Job	Run time
checks / readme-snippets	15s
checks / pre-commit	35s
checks / test (3.10, locked, windows-latest)	2m 11s
checks / test (3.10, lowest-direct, windows-latest)	2m 39s
checks / test (3.11, lowest-direct, windows-latest)	2m 37s
checks / test (3.11, lowest-direct, ubuntu-latest)	53s
checks / test (3.10, locked, ubuntu-latest)	46s
checks / test (3.11, locked, ubuntu-latest)	47s
checks / test (3.12, lowest-direct, ubuntu-latest)	58s
checks / test (3.12, locked, windows-latest)	3m 36s
checks / test (3.12, locked, ubuntu-latest)	50s
checks / test (3.10, lowest-direct, ubuntu-latest)	47s
checks / test (3.13, locked, ubuntu-latest)	42s
checks / test (3.14, lowest-direct, windows-latest)	2m 21s
checks / test (3.13, lowest-direct, ubuntu-latest)	44s
checks / test (3.13, lowest-direct, windows-latest)	2m 57s
checks / test (3.13, locked, windows-latest)	2m 32s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 10s
checks / test (3.14, locked, ubuntu-latest)	2m 21s
checks / test (3.14, locked, windows-latest)	3m 21s
checks / test (3.11, locked, windows-latest)	2m 26s
checks / test (3.12, lowest-direct, windows-latest)	3m 49s
all-green	6s
	39m 23s

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