[backport 2025.1] Update seastar submodule (no nested stall backtraces)

[xemul]

• seastar ed31c1ce...b2ff08a5 (1):

  stall_detector: no backtrace if exception

Fixes #24464

[scylladb-promoter]

:green_circle: CI State: SUCCESS

:white_check_mark: - Build :white_check_mark: - dtest with tablets :white_check_mark: - dtest with gossip topology changes :white_check_mark: - dtest with consistent topology changes :white_check_mark: - Unit Tests

Build Details:

• Duration: 6 hr 13 min
• Builder: i-00945cd408d109fde (m5d.16xlarge)

[xemul]

Promoted to branch-2025.1 (b6a4065ac1afaac54a3ed042205454c2570e7fdd) but not closed automatically , Cc @yaronkaikov