Upgrade Go to 1.18 and improve invocation output

Changelog for 0.6.0:

• PR #25 Improve output with duration of invocations and migrate to Go 1.18 by @alexellis

Commits
2268390 Improve output, migrate to Go 1.18 by @alexellis
f981570 Update docs for README by @alexellis
6e03b1a Update README.md by @alexellis

Changes: 0.5.1...0.6.0

Generated by Derek