Add missing content-type

Add_missing_content-type.patch

Index: src/Pim/Bundle/EnrichBundle/Resources/public/js/saver/base-saver.js
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- src/Pim/Bundle/EnrichBundle/Resources/public/js/saver/base-saver.js	(revision d1f975690b64872f3aecc4cc19e70b38d6febb60)
+++ src/Pim/Bundle/EnrichBundle/Resources/public/js/saver/base-saver.js	(date 1564996256000)
@@ -25,6 +25,7 @@
                     /* todo: remove ternary when all instances using this module will provide method parameter */
                     type: 'undefined' === typeof method ? 'POST' : method,
                     url: this.getUrl(code),
+                    contentType: 'application/json',
                     data: JSON.stringify(data)
                 }).then(function (entity) {
                     mediator.trigger('pim_enrich:form:entity:post_save', entity);