Update seastar submodule
Update seastar submodule

* seastar 5632cf2146...0fe32ec596 (11):
  > futures: Add a test for a broken promise in a parallel_for_each
  > future: Simplify finally_body implementation
  > futures_test: Extend nested_exception test
  > Merge "make gate methods noexcept" from Benny
  > tutorial: fix service_loop example
  > sharded: fix doxygen \example clause for sharded_parameter
  > Merge "future: Don't call need_preempt in 'then' and 'then_impl'" from Rafael
  > future: Refactor a bit of duplicated code
  > Merge "Add with_file helpers" from Benny
  > Merge "Fix doxygen warnings" from Benny
  > build: add doxygen to install-dependencies.sh

avikivity/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,avikivity/scylla,scylladb/scylla