Remove openssl-dev from Dockerfile

It is pulled by postgresql-dev anyway
In the upcoming alpine, openssl v3 will be
the default, but postgresql-dev will still
require openssl v1.x.
This creates a conflict, which can be resolved
if postgresql-dev can choose the openssl version
it depends on.

Author: cimnine

Dockerfile

@@ -17,7 +17,6 @@ RUN apk add --no-cache \
       make \
       musl-dev \
       openldap-dev \
-      openssl-dev \
       postgresql-dev \
       py3-pip \
       python3-dev \