Upgrade gds-api-adapters to 7.1.0

Needed to use parameters for Rummager's /search API.
Use the newer hash response format for searches

This is part of upgrading all clients, and then later we can make the hash
response_style the default.
Merge pull request #46 from alphagov/use_new_rummager_features_and_api

Use new rummager features and api