bazel: Update seastar

[StephanDollberg]

Update seastar pointer to latest.

Makes SEASTAR_ASSERT abort with SIGABRT and not SIGILL.

Backports Required

• none - not a bug fix
• none - this is a backport
• none - issue does not exist in previous branches
• none - papercut/not impactful enough to backport
• v25.2.x
• v25.1.x
• v24.3.x
• v24.2.x

Release Notes

• none

[vbotbuildovich]

CI test results

test results on build#69429

test_class	test_method	test_arguments	test_kind	job_url	test_status	passed	reason
MaintenanceTest	test_maintenance_sticky	{"use_rpk": false}	ducktape	https://buildkite.com/redpanda/redpanda/builds/69429#01983210-55d9-4a7a-b068-e3fa4ceec202	FLAKY	20/21	upstream reliability is '97.85992217898833'. current run reliability is '95.23809523809523'. drift is 2.62183 and the allowed drift is set to 50. The test should PASS