Handle connection errors in StreamableHTTP post_writer #1417

Job	Run time
checks / readme-snippets	27s
checks / pre-commit	41s
checks / test (3.10, lowest-direct, windows-latest)	2m 16s
checks / test (3.11, lowest-direct, ubuntu-latest)	53s
checks / test (3.11, lowest-direct, windows-latest)	2m 37s
checks / test (3.10, lowest-direct, ubuntu-latest)	56s
checks / test (3.12, locked, windows-latest)	3m 54s
checks / test (3.13, lowest-direct, ubuntu-latest)	54s
checks / test (3.12, locked, ubuntu-latest)	1m 22s
checks / test (3.14, locked, ubuntu-latest)	2m 24s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 5s
checks / test (3.10, locked, ubuntu-latest)	30s
checks / test (3.14, locked, windows-latest)	3m 23s
checks / test (3.11, locked, ubuntu-latest)	55s
checks / test (3.11, locked, windows-latest)	2m 35s
checks / test (3.13, locked, ubuntu-latest)	50s
checks / test (3.10, locked, windows-latest)	2m 18s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 23s
checks / test (3.14, lowest-direct, windows-latest)	2m 28s
checks / test (3.13, lowest-direct, windows-latest)	2m 42s
checks / test (3.13, locked, windows-latest)	3m 14s
checks / test (3.12, lowest-direct, windows-latest)	4m 28s
all-green	18s
	42m 33s

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