Update stan submodule

hsbadr · hsbadr · commit da412a0d6b3e · 2024-01-22T11:04:44.000-05:00
diff --git a/StanHeaders/inst/include/upstream b/StanHeaders/inst/include/upstream
@@ -1 +1 @@
-Subproject commit dd48b6733cc666b8c3297e46b7f53947d41a6758
+Subproject commit 9b2ae991405db7bf21e261f76f7f9a2fdcab9762
