Switch to GrapheneOS's hardened_malloc

This was suggested during the dev meeting of the 18/09/22.

It may break things and it may make things unbearably slow

core/base/Dockerfile

@@ -12,7 +12,8 @@ ARG MAILU_GID=1000
 RUN set -euxo pipefail \
   ; addgroup -Sg ${MAILU_GID} mailu \
   ; adduser -Sg ${MAILU_UID} -G mailu -h /app -g "mailu app" -s /bin/bash mailu \
-  ; apk add --no-cache bash ca-certificates curl python3 tzdata
+  ; apk add --no-cache bash ca-certificates curl python3 tzdata \
+  ; apk add --repository=http://dl-cdn.alpinelinux.org/alpine/edge/testing hardened-malloc
 
 WORKDIR /app
 

towncrier/newsfragments/2525.feature

@@ -0,0 +1 @@
+Switch to GrapheneOS's hardened_malloc