Avoid throwing an exception when the length of the params list is zero

[MrDave1999]

The SQL file loader should not throw an exception in this case, since it is not an error, i.e. if the consumer passes an empty collection as argument, then the expected behavior is to return an empty dictionary without SQL statements.

This also facilitates integration with the plugin-based architecture, since the host application can decide not to load any plugins, so the host application would be passing to the SQL file loader an empty collection as argument and the expected behavior is not to throw an exception, but to return to the consumer an empty dictionary without SQL statements.

This also avoid tests from failing from PR #89.
See the jobs: https://github.com/ose-net/yesql.net/actions/runs/7496291700/job/20408051876#step:4:223