minor, use py3's open(encoding=)
diff --git a/test/subset/generate-expected-outputs.py b/test/subset/generate-expected-outputs.py
index 286de8d..2e94e4e 100755
--- a/test/subset/generate-expected-outputs.py
+++ b/test/subset/generate-expected-outputs.py
@@ -3,7 +3,6 @@
 # Pre-generates the expected output subset files (via fonttools) for
 # specified subset test suite(s).
 
-import io
 import os
 import sys
 
@@ -32,7 +31,7 @@
 	usage()
 
 for path in args:
-	with io.open(path, mode="r", encoding="utf-8") as f:
+	with open(path, mode="r", encoding="utf-8") as f:
 		test_suite = SubsetTestSuite(path, f.read())
 		output_directory = test_suite.get_output_directory()