postgresql yum repos no found postgresql11-11.1-1PGDG.rhel7.x86_64.rpm

I have used postgresql11-11.1 in my project based on the centos7 x86-64 system. But I found  postgresql11-11.1/postgresql11-contrib-11.1 rpm already removed from the repos list.

https://download.postgresql.org/pub/repos/yum/11/redhat/rhel-7-x86_64/  

Can you help me:

1. why postgresql download repos remove redhat postgresql 11.1 version rpm?

2. where can I find postgresql11.1 rpm?

3. do I need upgrade postgresql version?

Thinks for your help!