Update to use more recent ff-test-cases submodule

stephenmcconkey · stephenmcconkey · commit 313c3979becf · 2022-10-04T16:36:54.000+01:00
diff --git a/tests/ff-test-cases b/tests/ff-test-cases
@@ -1 +1 @@
-Subproject commit b79d82fd5d80ef47a1c13e2e2bffd4a45a2e56b7
+Subproject commit 6e782f1b954f01feae622f707dbfef38a264476b
