[ixpmanager] Upgrade 5.2.0

[Barry O'Donovan]

Shahab,

Shahab Vahabzadeh wrote on 23/03/2020 19:52:
> Can you introduce safest way to upgrade 5.2.0 to 5.5.0?

Unless you are proficient with PHP, Laravel and Doctrine, then the 
safest and advised way to do this is to step through the minor versions 
and follow the release notes for each.

I.e. 5.2.0 -> 5.3.0 -> 5.4.0 -> 5.5.0

Once you get into the flow, upgrading can be done fairly quickly (but 
then I would say that ;-) ).

  - Barry