mastodon_db_backup.sh - disable TTY on docker-compose; use pipefail

Script ran fine on the console, failed in cron job.  This is because
the docker-compose exec command was attempting (by default) to allocate
 a TTY, and failing.  This was also not being detected because the
default bash behaviour is to return the status of the last command
in a pipe (in this case, gzip). Enable pipefail option to prevent this.

backups/mastodon_db_backup.sh

 #!/bin/bash
 
 # A script which backs up the mastodon database(s)
+set -o pipefail
+set -e
 
 container=db
 backupdir=/opt/backups/postgres
@@ -21,7 +23,7 @@ backup() {
   rm -f $(readlink -f "$backupdir/$link")
 
   # create new backup file
-  docker-compose -f /opt/social.coop/sauce/docker/docker-compose.yml exec "$cname" pg_dumpall -U postgres -c -v | gzip >"$backupdir/$file"
+  docker-compose -f /opt/social.coop/sauce/docker/docker-compose.yml exec -T "$cname" pg_dumpall -U postgres -c -v | gzip >"$backupdir/$file"
   status=$?
 
   # link the sequence number to it