Improvements

• #5533: Support for
  PostgreSQL schemas in
  sql-tracker-store. The SQLTrackerStore
  accesses schemas defined by the POSTGRESQL_SCHEMA environment variable if
  connected to a PostgreSQL database.

  The schema is added to the connection string option's -csearch_path key, e.g.
  -options=-csearch_path=<SCHEMA_NAME> (see
  https://www.postgresql.org/docs/11/contrib-dblink-connect.html for more details).
  As before, if no POSTGRESQL_SCHEMA is defined, Rasa uses the database's default
  schema (public).

  The schema has to exist in the database before connecting, i.e. it needs to have been
  created with

  CREATE SCHEMA schema_name;
  

Bugfixes

• #5547: Fixed ambiguous logging in DIETClassifier by adding the name of the calling class to the log message.