update-deps: exclude timestamps

* tool/update-deps (concentrate): exclude timestamps for
  directories.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55586 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

tool/update-deps

@@ -397,6 +397,8 @@ def concentrate(dependencies, cwd)
       if %r{\A\.\.(/|\z)} =~ s.to_s
         warn "warning: out of tree source: #{s}"
         true
+      elsif %r{/\.time\z} =~ s.to_s
+        true
       else
         false
       end