Update self_hosted_patch.yml

Signed-off-by: elseif <elseif@live.cn>

.github/workflows/self_hosted_patch.yml

@@ -413,6 +413,11 @@ jobs:
         sudo apt-get install -y qemu-utils extlinux > /dev/null
         truncate --size 128M install-image-$LATEST_VERSION.img
         sudo qemu-nbd -c /dev/nbd0 -f raw install-image-$LATEST_VERSION.img
+        while [ ! -e "/dev/nbd0p1" ]; do
+          echo "wait $part ..."
+          sleep 0.2
+        done
+        sudo lsblk /dev/nbd0
         sudo mkfs.vfat -n "Install" /dev/nbd0
         sudo mkdir ./install
         sudo mount /dev/nbd0 ./install