Allow Doctrine ORM v3

[emodric]

🎫 Issue	IBX-11061

Description:

As far as I can see, Doctrine ORM integration into Ibexa Core is pretty thin, so this should work without any issues.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Steveb-p]

Only other package that uses doctrine/orm is closed source ibexa/taxonomy. Initial checks that I've done show that upgrading to ORM v3 seems to work - would need to run regression tests that everything works and does not break + explicitly check against both v2 and v3 when possible.

To be honest, I'm pretty sure we intended to actually remove doctrine/orm direct dependency in 5.x. OSS itself does not make use of Doctrine ORM functionality afaik.