🐛 Fix bug preventing non-utf8 characters being saved in some databases

[hi019]

Fixes gofiber/fiber#1258

TODO:

• Write migration instructions
• Create schema check function for Postgres
• Create schema check function for MySQL
• Create schema check function for SQLITE
• Move migration instructions to MIGRATION.md

Postgres:

ALTER TABLE fiber_storage 
ALTER COLUMN v TYPE BYTEA USING v::bytea;

MYSQL:

ALTER TABLE fiber_storage MODIFY COLUMN v BLOB;

[hi019]

LGTM

[ReneWerner87]

Thx