bump gossamer commit

diff --git a/gossamer b/gossamer
index 81cf378fb8d49e8ed73cc6c2bac1033df593e53e..a973180b68869e1c803b27e5b9e136b2cefe582e 160000 (submodule)
--- a/gossamer
+++ b/gossamer
@@ -1 +1 @@
-Subproject commit 81cf378fb8d49e8ed73cc6c2bac1033df593e53e
+Subproject commit a973180b68869e1c803b27e5b9e136b2cefe582e