Fixed missing backslash by separating ENV lines again

Dockerfile

@@ -17,15 +17,14 @@ RUN \
     mkdir -p /mnt/restic /var/spool/cron/crontabs /var/log; \
     touch /var/log/cron.log;
 
-ENV \
-    RESTIC_REPOSITORY=/mnt/restic \
-    RESTIC_PASSWORD="" \
-    RESTIC_TAG="" \
-    NFS_TARGET="" \
-    BACKUP_CRON="0 */6 * * *" \
-    RESTIC_FORGET_ARGS="" \
-    RESTIC_JOB_ARGS=""
-    MAILX_ARGS=""
+ENV RESTIC_REPOSITORY=/mnt/restic
+ENV RESTIC_PASSWORD=""
+ENV RESTIC_TAG=""
+ENV NFS_TARGET=""
+ENV BACKUP_CRON="0 */6 * * *"
+ENV RESTIC_FORGET_ARGS=""
+ENV RESTIC_JOB_ARGS=""
+ENV MAILX_ARGS=""
 
 # /data is the dir where you have to put the data to be backed up
 VOLUME /data