Update some PMPro DB tables to use UTF8 character sets.

fix-charset-for-pmpro-tables.sql

# PMPro doesn't set the character set when creating its tables.
# So on install PMPro will use the default character set for your DB.
# In some cases this might be something like latin1, which will not
# work with special characters for non-latin languages, e.g. Hebrew.
# To fix this, you can update the character set on these tables using MySQL.
#
# IMPORTANT: Back up your DB (at least these tables) before running any queries.
ALTER TABLE wp_pmpro_membership_levels CONVERT TO CHARACTER SET utf8;
ALTER TABLE wp_pmpro_membership_levelmeta CONVERT TO CHARACTER SET utf8;
ALTER TABLE wp_pmpro_membership_ordermeta CONVERT TO CHARACTER SET utf8;