✅ Update backport for ruby 2.7 compatibility

Author: nevans

test/net/imap/test_sequence_set.rb

@@ -101,7 +101,7 @@ def compare_to_reference_set(nums, set, seqset)
     dup = set.dup
     result = transform.to_proc.(set)
     assert_equal dup, set, "transform should not modified"
-    if data in {freeze: :always}
+    if data[:freeze] == :always
       assert result.frozen?, "this transform always returns frozen"
     else
       refute result.frozen?, "transform of non-frozen returned frozen"