src/seastar: update seastar submodule to fix prometheus build failure

Fixes: https://tracker.ceph.com/issues/64589
Signed-off-by: Samuel Just <sjust@redhat.com>

diff --git a/src/seastar b/src/seastar
index f3a1484c83b8b8ed774582f85fe33bf957390400..1a2cd05b7bf515f68841fa06ba9e3bdaecd20716 160000 (submodule)
--- a/src/seastar
+++ b/src/seastar
@@ -1 +1 @@
-Subproject commit f3a1484c83b8b8ed774582f85fe33bf957390400
+Subproject commit 1a2cd05b7bf515f68841fa06ba9e3bdaecd20716