fix the linux/arm/v7 build

core/base/Dockerfile

@@ -8,11 +8,13 @@ ENV TZ=Etc/UTC LANG=C.UTF-8
 
 ARG MAILU_UID=1000
 ARG MAILU_GID=1000
+ARG TARGETPLATFORM
 
 RUN set -euxo pipefail \
   ; addgroup -Sg ${MAILU_GID} mailu \
   ; adduser -Sg ${MAILU_UID} -G mailu -h /app -g "mailu app" -s /bin/bash mailu \
   ; apk add --no-cache bash ca-certificates curl python3 tzdata \
+  ; if [[ "$TARGETPLATFORM" == 'linux/arm/v7' ]]; then exit;fi \
   ; machine="$(uname -m)" \
   ; if [[ "${machine}" == x86_64 || "${machine}" == armv8* || "${machine}" == aarch64 ]] \
   ; then \