[ruyi-reimu] Board image openwrt-sifive-unmatched need update

[hakuzousu]

Description

• In upstream repo https://downloads.openwrt.org/releases/, the latest version is 23.05.3

[weilinfox]

Need update https://mirror-03.infra.openwrt.org/releases/23.05.3/targets/sifiveu/generic/openwrt-23.05.3-sifiveu-generic-sifive_unmatched-ext4-sdcard.img.gz