[2.3.0] Checkmk Werk 16603 created: mk_postgres: Ensure coherent string encoding

[//]: # (werk v2) # mk_postgres: Ensure coherent string encoding key | value ---------- | --- date | 2024-03-27T08:43:36+00:00 version | 2.3.0b4 class | fix edition | cre component | checks level | 1 compatible | yes Postgres.cfg was always read as unicode decoded. This ensures that the read text is correctly converted to byte string format.