@std/yaml zero-started numeric strings stringify to numbers

**Describe the bug** zero-started numeric strings like '08' or '09' stringify to numbers **Steps to Reproduce** ```js import {stringify} from 'jsr:@std/yaml'; stringify('07'); // returns expected result "'07'\n" stringify('08'); // returns unexpected result "08\n" stringify('09'); // returns unexpected result "09\n" ``` **Expected behavior** stringify('08') should return "'08'\n" stringify('09') should return "'09'\n" **Environment** - OS: Debian 13 - deno version: 2.7.4 (stable, release, x86_64-unknown-linux-gnu) - @std/yaml version: 1.0.12