Fix doctrine mapping

[core23]

Subject

The recent doctrine dbal update introduced a deprecation warning

 [FAIL] The entity-class App\Entity\Media\Media mapping is invalid:

 * The field 'App\Entity\Media\Media#length' has the property type 'float' that differs from the metadata field type 'string' returned by the 'decimal' DBAL type.

 [FAIL] The entity-class Sonata\MediaBundle\Entity\BaseMedia mapping is invalid:

 * The field 'Sonata\MediaBundle\Entity\BaseMedia#length' has the property type 'float' that differs from the metadata field type 'string' returned by the 'decimal' DBAL type.

 [FAIL] The entity-class Core23\MediaBundle\Entity\BaseMedia mapping is invalid:

 * The field 'Core23\MediaBundle\Entity\BaseMedia#length' has the property type 'float' that differs from the metadata field type 'string' returned by the 'decimal' DBAL type.

I am targeting this branch, because this is a patch.

Changelog

### Fixed
- Fix doctrine mapping for media length

[dmitryuk]

Please make a new release after merge

[dmitryuk]

@VincentLanglet can you make a new release?

[VincentLanglet]

@VincentLanglet can you make a new release?

Done https://github.com/sonata-project/SonataMediaBundle/releases/tag/4.10.5