DEV: Freeze time to avoid flakiness in scanned_upload_spec (#50)

We're using `eq_time` to compare expected timestamps. That only allows a 1ms leeway, so we gotta freeze time to make the spec reliable on slower machines

spec/models/scanned_upload_spec.rb

@@ -88,6 +88,7 @@
     end
 
     it "sets the next scan to one week from now after the first week" do
+      freeze_time
       upload.created_at = 1.week.ago
       scanned_upload.next_scan_at = nil
 
@@ -97,6 +98,7 @@
     end
 
     it "sets the next scan to x weeks in the future where x is the number of weeks since created" do
+      freeze_time
       upload.created_at = 2.weeks.ago
       scanned_upload.next_scan_at = 1.day.ago