fix Future cancellation when using SINGLE_URING

Florian Fischer (2):
      [SubmitActor] don't manually invalidate broken chains after linux 5.15
      [IoContext] do not use Future after allowing its destruction

 emper/io/IoContext.cpp   | 10 +++++-----
 emper/io/SubmitActor.cpp |  3 ++-
 2 files changed, 7 insertions(+), 6 deletions(-)