Support authentication with passwords that contain a colon (#41)

Co-authored-by: Pascal Hofmann <[email protected]>

client.go

@@ -29,7 +29,7 @@ func New(auth, baseURL string) (*Client, error) {
 	}
 	key := ""
 	if strings.Contains(auth, ":") {
-		split := strings.Split(auth, ":")
+		split := strings.SplitN(auth, ":", 2)
 		u.User = url.UserPassword(split[0], split[1])
 	} else {
 		key = fmt.Sprintf("Bearer %s", auth)