When Solr search engine is in use, content objects containing SEO Field Type cannot be published.

1. Create a new CT test and add SEO fieldtype to it.
2. Go to content structure and create a new test content object.
3. Fill in all the required forms and hit Publish.

Result:
You will be presented with the following error:

Field Type "ibexa_seo" is not indexable. Provide Ibexa\Contracts\Core\FieldType\Indexable implementation and register it with the "ibexa.field_type.indexable" tag.

Expected result:
Content object can be successfully published.