Mark Gemspec-reproducible change fixing #784225, too

I think the UTC date change will fix the Multi-Arch not-same file issue,
too.

Signed-off-by: Antonio Terceiro <terceiro@debian.org>
Signed-off-by: Christian Hofstaedtler <zeha@debian.org>

Gbp-Pq: Name Mark-Gemspec-reproducible-change-fixing-784225-too.patch

Author: sorah

lib/rubygems/specification.rb

@@ -1709,7 +1709,9 @@ def date=(date)
                 raise(Gem::InvalidSpecificationException,
                       "invalid date format in specification: #{date.inspect}")
               end
-            when Time, DateLike then
+            when Time then
+              Time.utc(date.utc.year, date.utc.month, date.utc.day)
+            when DateLike then
               Time.utc(date.year, date.month, date.day)
             else
               TODAY