fixes a leak on every REST request (#779)

per Do documentation: "If the returned error is nil, the Response will contain a non-nil Body which the user is expected to close."

Co-authored-by: Joel Dodge <joeldodge@google.com>

go/rtl/auth.go

@@ -132,6 +132,8 @@ func (s *AuthSession) Do(result interface{}, method, ver, path string, reqPars m
 	if err != nil {
 		return err
 	}
+	defer res.Body.Close()
+
 
 	if res.StatusCode < 200 || res.StatusCode > 226 {
 		return fmt.Errorf("response error: %s", res.Status)
@@ -209,4 +211,4 @@ func setQuery(u *url.URL, pars map[string]interface{}) {
 		}
 	}
 	u.RawQuery = q.Encode()
-}
+}