Remove Drupal 8 (#64)

* Remove Drupal 8

composer.json

 {
     "name": "islandora/jsonld",
-    "description": "JSON-LD serializer for Drupal 8",
+    "description": "JSON-LD serializer for Drupal",
     "type": "drupal-module",
     "license": "GPL-2.0+",
     "homepage": "https://github.com/Islandora/jsonld",

jsonld.info.yml

@@ -2,8 +2,7 @@ name: 'JSON-LD'
 type: module
 description: 'Serializes entities to JSON-LD / LDP for the Islandora Project'
 package: Web services
-core: 8.x
-core_version_requirement: ^8 || ^9
+core_version_requirement: ^9
 dependencies:
   - hal
   - serialization