Update NATS Streaming version

Changelog for 0.27.3:

• PR #1816 remove duplicates and fix order of adopters by @nitishkumar71
• PR #1810 chore: remove refs to deprecated io/ioutil by @testwill

Commits
9ba4a73 Rename Makefile targets by @alexellis
479285c fixed adopters by @nitishkumar71
4cf5fb8 Update contributing guide by @alexellis
ed5bd75 Rename to OpenFaaS by @alexellis
4f4e3d2 chore: remove refs to deprecated io/ioutil by @testwill

Changes: 0.27.2...0.27.3

Generated by Derek