Deprecated install on golang 1.17.8

[dotCipher]

with go version of go1.17.8 darwin/amd64 I get the following deprecation warning when running:

go get -u github.com/rakyll/gotest

go get: installing executables with 'go get' in module mode is deprecated.
	To adjust and download dependencies of the current module, use 'go get -d'.
	To install using requirements of the current module, use 'go install'.
	To install ignoring the current module, use 'go install' with a version,
	like 'go install example.com/cmd@latest'.
	For more information, see https://golang.org/doc/go-get-install-deprecation
	or run 'go help get' or 'go help install'.

What's the suggested method of install?

[subtlepseudonym]

This issue should be solved by #40, which updates the readme to specify that go install ... should be used.