clean up more dict iter warnings

Newer pylint catches more cases where we use dicts fields but outside
of an obvious iteration.  Force them through list() as makes sense.

BUG=chromium:1015273
TEST=`cros lint` is clean

Change-Id: I28207a7b5c1400b70094c67ba138be8d7b07a771
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1870893
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Michael Mortensen <mmortensen@google.com>
diff --git a/api/controller/artifacts_unittest.py b/api/controller/artifacts_unittest.py
index 11ab472..32af5b8 100644
--- a/api/controller/artifacts_unittest.py
+++ b/api/controller/artifacts_unittest.py
@@ -199,7 +199,7 @@
     # Verify the output proto is being populated correctly.
     self.assertTrue(self.response.artifacts)
     paths = [artifact.path for artifact in self.response.artifacts]
-    self.assertCountEqual(files.values(), paths)
+    self.assertCountEqual(list(files.values()), paths)
 
   def testBundleAutotestFiles(self):
     """BundleAutotestFiles calls service correctly."""
@@ -219,7 +219,7 @@
     # Verify the output proto is being populated correctly.
     self.assertTrue(self.response.artifacts)
     paths = [artifact.path for artifact in self.response.artifacts]
-    self.assertCountEqual(files.values(), paths)
+    self.assertCountEqual(list(files.values()), paths)
 
   def testInvalidOutputDir(self):
     """Test invalid output directory argument."""