pgAgent forces postgresql-9.4

I’ve installed PostgreSQL 12 on a XUbuntu 19.10.

After  “apt-get install pgagent”  there is a PostgreSQL 9.4 installed and running on Port 5433.

I’ve tried  “apt-get remove postgresql-9.4”  but this is installing “postgresql-9.5” instead.

I want to use pgagent with PostgreSQL 12 only – how?

Greetings from Berlin

-Stefan Wolf-