Updates the Stan submodule to 677398998.

stan-buildbot · stan-buildbot · commit b67ab56cc9be · 2024-10-02T06:04:56.000-04:00
diff --git a/stan b/stan
@@ -1 +1 @@
-Subproject commit a25ce482a17c24ebea8d95e9bec1fae8c96bfe30
+Subproject commit 677398998e7907c83d4cc8189a5ad4ade8cd2b34
