Removed querystring dep from members tests

refs: https://github.com/TryGhost/Toolbox/issues/158

- if we had to combine a large list of params then this would make sense
- we could/should also add a .query() method to our agent
- however, I don't think this is worthwhile/necessary for just 2 params right now :)

test/regression/api/admin/members.test.js

@@ -1,4 +1,3 @@
-const querystring = require('querystring');
 const assert = require('assert');
 const {agentProvider, mockManager, fixtureManager, matchers} = require('../../../utils/e2e-framework');
 const {anyString, anyArray, anyObjectId, anyEtag, anyUuid, anyErrorId, anyDate} = matchers;
@@ -50,7 +49,7 @@ describe('Members API', function () {
         };
 
         const {body} = await agent
-            .post(`members/?${querystring.stringify(queryParams)}`)
+            .post('/members/?send_email=true&email_type=signup')
             .body({members: [member]})
             .expectStatus(201)
             .matchBodySnapshot({