Add python3 support to cipd recipe module

Bug: 1227140
Change-Id: Id8bb07c90165a0c36741f0c797e17a227b043545
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3012230Reviewed-by: Anthony Polito <apolito@google.com>
Commit-Queue: Gavin Mak <gavinmak@google.com>

recipes/recipe_modules/cipd/test_api.py

@@ -57,7 +57,7 @@ class CIPDTestApi(recipe_test_api.RecipeTestApi):
       # Return one instance by default.
       return self._resultify([self.make_pin(package_name)])
     if isinstance(instances, int):
-      instances = ['instance_id_%i' % (i+1) for i in xrange(instances)]
+      instances = ['instance_id_%i' % (i+1) for i in range(instances)]
     return self._resultify([self.make_pin(package_name, instance)
                             for instance in instances])