challenge: Remove openntpd: doesn't work

pkg/challenge/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.15 AS mirror
+FROM alpine:edge AS mirror
 
 RUN mkdir -p /out/etc/apk/ && \
     cp /etc/apk/repositories /out/etc/apk/ && \
@@ -16,6 +16,7 @@ RUN apk add --no-cache --initdb -p /out \
     bind-doc \
     bind-tools \
     busybox \
+    busybox-doc \
     ca-certificates \
     curl \
     curl-doc \
@@ -33,12 +34,11 @@ RUN apk add --no-cache --initdb -p /out \
     kbd-bkeymaps \
     kbd-doc \
     kbd-vlock \
+    losetup \
     mandoc \
     man-pages \
     musl \
     nano \
-    openntpd \
-    openntpd-doc \
     openssh-client \
     openssh-doc \
     openssh-keygen \