Don't actually hit dl site (#1)

Reviewed-on: #1
Co-authored-by: jolheiser <john.olheiser@gmail.com>
Co-committed-by: jolheiser <john.olheiser@gmail.com>

dl.go

@@ -6,7 +6,7 @@ import (
 	"net/http"
 )
 
-const dlURL = "https://golang.org/dl/?mode=json"
+var dlURL = "https://golang.org/dl/?mode=json"
 
 // Version is a Go version
 type Version struct {

dl_test.go

@@ -14,7 +14,7 @@ func TestVersions(t *testing.T) {
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		_, _ = w.Write(dlResp)
 	}))
-	http.DefaultClient = server.Client()
+	dlURL = server.URL
 
 	versions, err := Versions(context.Background())
 	if err != nil {