Add debootstrap to dependency check in the rockpi build

Signed-off-by: Henry Speiser <henry@speiser.net>
Change-Id: I929340c14cae4f638bfb133a059328ac20130bbe
diff --git a/frc971/rockpi/build_rootfs.sh b/frc971/rockpi/build_rootfs.sh
index 5625127..12dceae 100755
--- a/frc971/rockpi/build_rootfs.sh
+++ b/frc971/rockpi/build_rootfs.sh
@@ -18,6 +18,7 @@
     gcc-aarch64-linux-gnu
     device-tree-compiler
     swig
+    debootstrap
 )
 for dep in "${REQUIRED_DEPS[@]}"; do
     if ! dpkg-query -W -f='${Status}' "${dep}" | grep -q "install ok installed"; then