Release version 0.4.3

[qnikst]

See branch: https://github.com/haskell-distributed/distributed-process-tests/tree/release-0.4.3

Checklist:

• Tests works with this release (see https://github.com/haskell-distributed/cloud-haskell/issues/3)
• All relevant patches are included
• Signed tag on the bump
• Upload to hackage