Fix embed test 0007 context/frame.

Author: gkellogg

tests/new-embed-api/frame-0007-frame.jsonld

@@ -1,7 +1,8 @@
 {
   "@context": {
     "dc": "http://purl.org/dc/elements/1.1/",
-    "ex": "http://example.org/vocab#"
+    "ex": "http://example.org/vocab#",
+    "ex:relatesTo": {"@type": "@id"}
   },
   "@type": "ex:Library",
   "@embed": "@always",

tests/new-embed-api/frame-0007-in.jsonld

@@ -5,7 +5,8 @@
     "dc:subject": {"@type": "@id"},
     "ex:contains": {"@type": "@id"},
     "ex:bookmark": {"@type": "@id"},
-    "ex:topic": {"@type": "@id"}
+    "ex:topic": {"@type": "@id"},
+    "ex:relatesTo": {"@type": "@id"}
   },
   "@graph": [
     {

tests/new-embed-api/frame-0007-out.jsonld

@@ -1,7 +1,8 @@
 {
   "@context": {
     "dc": "http://purl.org/dc/elements/1.1/",
-    "ex": "http://example.org/vocab#"
+    "ex": "http://example.org/vocab#",
+    "ex:relatesTo": {"@type": "@id"}
   },
   "@graph": [
     {