Use required name of ld2h package.

PHP code currently assumes package is named ld2h.

Author: jaudriga

package.json

@@ -2,6 +2,6 @@
   "name": "roundcube-structured-email",
   "version": "1.0.0-alpha",
   "dependencies": {
-    "jsonld2html-cards": ">=1.0.0-beta"
+    "ld2h": ">=1.0.0-beta"
   }
 }