update submodule to v3.1.0

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

diff --git a/upstream b/upstream
index 1777d9992c194d6ca90556134731208303f786b1..e17ac2503ccd41256aa4be078bb81e520a5b1c7f 160000 (submodule)
--- a/upstream
+++ b/upstream
@@ -1 +1 @@
-Subproject commit 1777d9992c194d6ca90556134731208303f786b1
+Subproject commit e17ac2503ccd41256aa4be078bb81e520a5b1c7f