MySQL 5.6 support

[Nemo64]

Q	A
DoctrineAuditBundle version	3.3.2
PHP version	7.3.14
Database	MySQL 5.6.47 (ORM version 2.7.0)

Summary

The the Indexes on object_id, discriminator and blame_id are too long for MySQL 5.6.

Current behavior

In strict mode I'll get an error: Specified key was too long; max key length is 767 bytes.
In normal mode MySQL will truncate the index to eg. object_id(191) which is fine, but every time I create a migration dbal will try to migrate from object_id(191) to just object_id.

This is actually an issue with dbal: doctrine/dbal#3419
But that issue is so old that probably nobody cares about it and the most simple fix could be within the schema here even though it's a bit of a hack

How to reproduce

Just use MySQL 5.6. I recommend the docker image.

Expected behavior

Not that easy. Either the index must always be shortened to 191 or there must be a detection for mysql 5.6 in place.

Another alternative would be to not encode the existing fields with utf8 but in binary since text feature are not really required here but that would change the schema for everyone already using this bundle

The reason I care for that old MySQL is because I use AWS Aurora Serverless which is only 5.6 compatible. But my local testing runs on a real MySQL 5.6.47