Raise bounds of hw-kafka-client to < 5.1 in order to allow version 5.0.0?

[alaendle]

haskell-libraries/nri-kafka/nri-kafka.cabal

Line 72 in f9698d5

, hw-kafka-client >=4.0.3 && <5.0

This would also help resolve commercialhaskell/stackage#6388 (at least after a update nri-kafka was published).