config schema incorrectly states that process manager connection must be a string

[C-Loftus]

In the docs for the postgresql manager it states the connection must include multiple properties like the password and username

This makes sense and works as expected, but if you run pygeoapi config validate --config pygeoapi.config.yml it causes an error:

jsonschema.exceptions.ValidationError: {'host': '127.0.0.1', 'port': 5432, 'database': 'db', 'user': 'postgres', 'password': 'password'} is not of type 'string'

Failed validating 'type' in schema['properties']['server']['properties']['manager']['properties']['connection']:
    {'type': 'string',
     'description': 'connection info to store jobs (e.g. filepath)'}

On instance['server']['manager']['connection']:
    {'host': '127.0.0.1',
     'port': 5432,
     'database': 'db',
     'user': 'postgres',
     'password': 'password'}

This seems to be due to the fact the the json schema states that the connection must be a string, fails early, and thus prevents config validation on other parts of the config

pygeoapi/pygeoapi/resources/schemas/config/pygeoapi-config-0.x.yml

Lines 134 to 136 in 6a35ff0

	connection:
	type: string
	description: connection info to store jobs (e.g. filepath)

(This was produced on pygeoapi, version 0.22.dev0 on MacOS)