update ifupdown2 submodule

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

diff --git a/ifupdown2 b/ifupdown2
index e665b9f166fd07bb3627fd289aa07eb8fa5a0782..288a88d3e432c312c684c435eff9104be1f22953 160000 (submodule)
--- a/ifupdown2
+++ b/ifupdown2
@@ -1 +1 @@
-Subproject commit e665b9f166fd07bb3627fd289aa07eb8fa5a0782
+Subproject commit 288a88d3e432c312c684c435eff9104be1f22953