When the connection url does not have an explicit driver, default to the provider driver

[doublebyte1]

Overview

Currently, these are the versions being installed by the CI;

• psycopg2 2.9.13
• SQLAlchemy 2.1.1

In SQAlchemy 2.1, the default driver changed to psycopg. However, pygeoapi is installing psycopg2. This mistmatch between what is installed, and the default driver that SQAlchemy expects, creates the issue described on #2424

This PR addresses the issue by letting the postgresql provider fallback to the backend provider driver. This approach avoids using the default SQAlchemy driver (which is not installed) and also pinning down dependencies.

A test was also added for creating a connection using the provider driver.

Related Issue / discussion

#2424

Additional information

Dependency policy (RFC2)

• I have ensured that this PR meets RFC2 requirements

Updates to public demo

• I have ensured that breaking changes to the pygeoapi master demo server have been addressed
  • https://github.com/geopython/demo.pygeoapi.io/blob/master/services/pygeoapi_master/local.config.yml

Contributions and licensing

(as per https://github.com/geopython/pygeoapi/blob/master/CONTRIBUTING.md#contributions-and-licensing)

• I'd like to contribute [feature X|bugfix Y|docs|something else] to pygeoapi. I confirm that my contributions to pygeoapi will be compatible with the pygeoapi license guidelines at the time of contribution
• I have already previously agreed to the pygeoapi Contributions and Licensing Guidelines

[tomkralidis]

Thanks @doublebyte1. Can you fix flake8 errors in CI? Thanks.

[webb-ben]

Would the solution not be changing the driver_name in https://github.com/doublebyte1/pygeoapi/blob/0b3838011d54d01189f9cf937c557c4de35d41cb/pygeoapi/provider/sql.py#L810?

Will also note that #2251 introduced full connection strings:

data: postgresql://user:password@host:5432/db

[doublebyte1]

Would the solution not be changing the driver_name in https://github.com/doublebyte1/pygeoapi/blob/0b3838011d54d01189f9cf937c557c4de35d41cb/pygeoapi/provider/sql.py#L810?

Will also note that #2251 introduced full connection strings:

data: postgresql://user:password@host:5432/db

That would be a solution, if everyone would use SQALchemy >=2.1. If someone is using an earlier version, than the driver would stil be psycog2. If we really want to be that specific, perhaps we should pin down SQAlchemy here?

pygeoapi/requirements.txt

Line 17 in 0b38380

SQLAlchemy