ceph-object-corpus: do not try to decode pre-hammer ObjectStore::Transactions

We don't understand collection_attr any more.

Signed-off-by: Sage Weil <sage@redhat.com>

diff --git a/ceph-object-corpus b/ceph-object-corpus
index 7bd9bbe235c59527dd1ab192fed21944da686d20..20351c6bae6dd4802936a5a9fd76e41b8ce2bad0 160000 (submodule)
--- a/ceph-object-corpus
+++ b/ceph-object-corpus
@@ -1 +1 @@
-Subproject commit 7bd9bbe235c59527dd1ab192fed21944da686d20
+Subproject commit 20351c6bae6dd4802936a5a9fd76e41b8ce2bad0