update test data date format

Author: katrinSaleschus

gitlab4j-api/src/test/resources/org/gitlab4j/api/commit.json

@@ -6,10 +6,10 @@
   "author_email": "dmitriy.zaporozhets@gmail.com",
   "committer_name": "Dmitriy",
   "committer_email": "dmitriy.zaporozhets@gmail.com",
-  "created_at": "2012-09-20T06:06:12Z",
+  "created_at": "2012-09-20T06:06:12.248Z",
   "message": "Sanitize for network graph",
-  "committed_date": "2012-09-20T06:06:12Z",
-  "authored_date": "2012-09-20T06:06:12Z",
+  "committed_date": "2012-09-20T06:06:12.248Z",
+  "authored_date": "2012-09-20T06:06:12.248Z",
   "parent_ids": [
     "ae1d9fb46aa2b07ee9836d49862ec4e2c46fbbba"
   ],

gitlab4j-api/src/test/resources/org/gitlab4j/api/merge-request-system-hook-event.json

@@ -84,7 +84,7 @@
     "last_commit": {
       "id": "ba3e0d8ff79c80d5b0bbb4f3e2e343e0aaa662b7",
       "message": "fixed readme",
-      "timestamp": "2017-09-26T16:12:57Z",
+      "timestamp": "2017-09-26T16:12:57.248Z",
       "url": "http://example.com/awesome_space/awesome_project/commits/da1560886d4f094c3e6c9ef40349f7d38b5d27d7",
       "author": {
         "name": "GitLab dev user",

gitlab4j-api/src/test/resources/org/gitlab4j/api/merge-request.json

@@ -9,9 +9,9 @@
     "detailed_merge_status": "can_be_merged",
     "upvotes":0,
     "downvotes":0,
-    "created_at": "2016-12-03T17:23:34Z",
-    "updated_at": "2016-12-03T17:23:34Z",
-    "merged_at": "2016-12-03T17:23:34Z",
+    "created_at": "2016-12-03T17:23:34.248Z",
+    "updated_at": "2016-12-03T17:23:34.248Z",
+    "merged_at": "2016-12-03T17:23:34.248Z",
     "squash_commit_sha": "37a1f246848c3dc2bb82964a183417e2e72fe1a7",
     "merged_by": {
         "id": 7,
@@ -36,15 +36,15 @@
         "email":"admin@local.host",
         "name":"Administrator",
         "state":"active",
-        "created_at":"2012-04-29T08:46:00Z"
+        "created_at":"2012-04-29T08:46:00.248Z"
     },
     "assignee":{
         "id":1,
         "username": "admin",
         "email":"admin@local.host",
         "name":"Administrator",
         "state":"active",
-        "created_at":"2012-04-29T08:46:00Z"
+        "created_at":"2012-04-29T08:46:00.248Z"
     },
     "allow_collaboration": false,
     "allow_maintainer_to_push": false,