Here's a short go.mod:

module "github.com/you/hello"

require (
	"golang.org/x/text" v0.0.0-20180208041248-4e4a3210bb54
	"rsc.io/quote" v1.5.2
)

I propose to drop the distinction between a quoted string and a bare literal, with the restriction that literals must not include any kind of unicode space, nor U+0022 (") nor U+0060 (`). Then this file can be shortened to (and would be rewritten canonically as):

module github.com/you/hello

require (
	golang.org/x/text v0.0.0-20180208041248-4e4a3210bb54
	rsc.io/quote v1.5.2
)

Not quoting should make it easier to copy and paste from the command line or from substrings of import paths or from "go list -m" output. Backslashes are allowed in literals and stand for themselves, so that you can write

replace rsc.io/quote v1.5.2 => c:\work\quote

If you need a space in the path in that form then it's still necessary to quote:

replace rsc.io/quote v1.5.2 => `c:\rsc\my work\quote`
replace rsc.io/quote v1.5.2 => "/users/rsc/my work/quote"