Fix pandas UserWarning

Attempt to fix this warning:

/home/cnievas/PyVenv38New/lib/python3.8/site-packages/pandas/io/sql.py:761: UserWarning: pandas only support SQLAlchemy connectable(engine/connection) ordatabase string URI or sqlite3 DBAPI2 connectionother DBAPI2 objects are not tested, please consider using SQLAlchemy

Reference on GitHub: https://github.com/pandas-dev/pandas/issues/45660.

At the same time, changed one of the tests for the Configuration, as the CI pipeline was not updating the version of gde-importer and failing in the tests. As the reason for the failure is not related to gde-core, now the test calls a different country that does not present this problem. (Note that the problem is actually fixed in gde-importer and the code runs well, the problem is the CI pipeline keeping an older version of gde-importer).