Introduce & verify tls/ssl support

[affejunge]

Hi all,

We observed that using the Client with connection parameters like this
Client.open(f"dbname='stac' user='{username}' password='{password}' host='{host}' port=5432 sslmode='require'")

on a database with ssl enabled, the connection is not established. The error message is

PgstacError: postgres: error performing TLS handshake: no TLS implementation configured

Using psycopg2 with the same connection parameters works fine. The connection is established and a query is executed successfully.
We tested with this 4976448
against db running pgstac:v0.9.1

[gadomski]

Thanks for the report ... can you again after reinstalling? pip install --force git+https://github.com/stac-utils/pgstacrs. I've got a fix in #18 but haven't yet cooked up an easy way to test it.