Add correct BASE_IMAGE for aarch64.

build-docker.sh

@@ -77,7 +77,14 @@ BUILD_OPTS="$(echo "${BUILD_OPTS:-}" | sed -E 's@\-c\s?([^ ]+)@-c /config@')"
 # Check the arch of the machine we're running on. If it's 64-bit, use a 32-bit base image instead
 case "$(uname -m)" in
   x86_64|aarch64)
-    BASE_IMAGE=i386/debian:buster
+    case "$(uname -m)" in
+        aarch64)
+            BASE_IMAGE=arm32v7/debian:buster
+            ;;
+        *)
+            BASE_IMAGE=i386/debian:buster
+            ;;
+    esac
     ;;
   *)
     BASE_IMAGE=debian:buster