Fix go.mod path

[r-n-o]

After #9 was merged and v0.3.4 released we noticed failures to install the latest version of the go package:

$ go install github.com/tkhq/tkcli@latest
go: downloading github.com/tkhq/tkcli v0.3.4
go: github.com/tkhq/tkcli@latest: module github.com/tkhq/tkcli@latest found (v0.3.4), but does not contain package github.com/tkhq/tkcli

Specifying the folder doesn't work either:

$ go install -v github.com/tkhq/tkcli/src@latest
go: github.com/tkhq/tkcli/src@latest: github.com/tkhq/tkcli/src@v0.0.0-20230413013040-6938a0c3d432: parsing go.mod:
	module declares its path as: github.com/tkhq/tkcli
	        but was required as: github.com/tkhq/tkcli/src

This mini-diff should fix the issue!

I tagged/released this as v0.3.5-beta2 and src/v0.3.5-beta2 (yes, prefixed tags...😮‍💨). And it works as far as I can tell:

go install github.com/tkhq/tkcli/src@v0.3.5-beta2
go: downloading github.com/tkhq/tkcli v0.3.5-beta2
go: downloading github.com/tkhq/tkcli/src v0.3.5-beta2

[r-n-o]

Closing this PR. We've decided installing with go install isn't something we want to support long-term. Given turnkey CLI is supposed to be used as a binary, it makes little sense to distribute it that way. We have 3 install options documented in our README, let's stick to those!