ValidPrerelease should end in $

[jeremycarroll]

I was reading the code and came across:

const ValidPrerelease string = `^([0-9A-Za-z\-]+(\.[0-9A-Za-z\-]+)*)`

in version.go. I don't know go, but it seems to me to mis-implement the metadata extension, in that this regex matches '0==='
i.e.

	matched, err := regexp.MatchString(`^([0-9A-Za-z\-]+(\.[0-9A-Za-z\-]+)*)`, "0===")

gives true, nil.

[mattfarina]

Closing as this was merged.