Add test stubs for Graph API remove

Author: pluma

test/19-graph-vertex-collections.js

@@ -1,6 +1,9 @@
 import {describe, it} from 'mocha';
 
 describe('GraphVertexCollection API', () => {
+  describe('graphVertexCollection.remove', () => {
+    it('is missing tests');
+  });
   describe('graphVertexCollection.vertex', () => {
     it('is missing tests');
   });

test/20-graph-edge-collections.js

@@ -1,6 +1,9 @@
 import {describe, it} from 'mocha';
 
 describe('GraphEdgeCollection API', () => {
+  describe('graphEdgeCollection.remove', () => {
+    it('is missing tests');
+  });
   describe('graphEdgeCollection.edge', () => {
     it('is missing tests');
   });