seastar: bump up seastar submodule version

Signed-off-by: Matan Breizman <mbreizma@redhat.com>

diff --git a/src/seastar b/src/seastar
index 50c6790df3db6ab38b5fea7e03494828dc2aafdc..f3a1484c83b8b8ed774582f85fe33bf957390400 160000 (submodule)
--- a/src/seastar
+++ b/src/seastar
@@ -1 +1 @@
-Subproject commit 50c6790df3db6ab38b5fea7e03494828dc2aafdc
+Subproject commit f3a1484c83b8b8ed774582f85fe33bf957390400