link to postgresql-common changed to deb11

Author: monk-afk

postgresql_setup.md

@@ -15,7 +15,7 @@ Table of Contents
 - Install GnuPG from apt, and get postgres-common package which contains a shell script for importing the postgresql repository keyring:
 ```sh
 root@host:~# apt-get install gnupg2 && \
-wget http://deb.debian.org/debian/pool/main/p/postgresql-common/postgresql-common_225.tar.xz && \
+wget http://deb.debian.org/debian/pool/main/p/postgresql-common/postgresql-common_225+deb11u1.tar.xz && \
 tar -xf postgresql-common_225.tar.xz && rm postgresql-common_225.tar.xz && \
 mkdir -p /usr/share/postgresql-common/pgdg && \
 mv ./postgresql-common/pgdg/apt.postgresql.org.sh /usr/share/postgresql-common/pgdg/ && \