Fix Httparty call in SlackWebhook
This is a follow-up of !257 (merged) and !259 (merged) that did fix some bugs but not all.
This fixes an issue where in_progress_mr.url
in Rakefile
returns nil
. That's because open_merge_requests.first
in UpstreamMergeService
returns a Gitlab::ObjectifiedHash
so we need to instantiate an UpstreamMergeRequest
object, and be sure that its #created_at
is actually a Time
.