Update merge_packages.sh

[senhao-xu]

https://github.com/xiaorouji/openwrt-passwall/trunk/brook doesn't exist update https://github.com/xiaorouji/openwrt-passwall/brook https://github.com/xiaorouji/openwrt-passwall/trunk/chinadns-ng doesn't exist update https://github.com/xiaorouji/openwrt-passwall/chinadns-ng https://github.com/xiaorouji/openwrt-passwall/trunk/trojan-go doesn't exist update https://github.com/xiaorouji/openwrt-passwall/trojan-go https://github.com/xiaorouji/openwrt-passwall/trunk/trojan-plus doesn't exist update https://github.com/xiaorouji/openwrt-passwall/trojan-plus