technical debts (#3438)

* reformat release notes
* deactivate transactions in migrations by default
* fix migration base class
* fix default value
* composer update

config/packages/doctrine_migrations.yaml

@@ -6,3 +6,4 @@ doctrine_migrations:
         # namespace is arbitrary but should be different from App\Migrations
         # as migrations classes should NOT be autoloaded
         'DoctrineMigrations': '%kernel.project_dir%/src/Migrations'
+    transactional: false