utf8mb4 is a superset of utf8 and thus is compatible. We should not
force an entire db change upon people who have proactively set utf8mb4
encoding before now.
This patch also removed the deprecated use of ->tables stanza in favour
of the table_info stanza.
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com> Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com> Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>