fixed cron daily filename

Dockerfile

@@ -4,7 +4,7 @@ COPY ./backup/pg_backup.config /etc/pg_backup.config
 
 COPY ./backup/pg_backup_rotated.sh /usr/local/bin/pg_backup_rotated.sh
 
-COPY ./backup/pg_backup_rotated.cron.sh /etc/cron.daily/pg_backup_rotated.cron.sh
+COPY ./backup/pg_backup_rotated.cron.sh /etc/cron.daily/pg_backup_rotated
 
 COPY ./run.sh /run.sh