Queries might fail with UnicodeDecodeError

[retifrav]

Some queries, such as this one:

-- https://gea.esac.esa.int/tap-server/tap
SELECT table_name, description
FROM tap_schema.tables
WHERE table_name = 'gaiadr2.dr1_neighbourhood'

might fail with the following error:

UnicodeDecodeError: 'ascii' codec can't decode byte 0xa0 in position 1317: ordinal not in range(128)

This is an bug in PyVO.