update sources to Ubuntu-5.15.0-20.20

(generated with debian/scripts/import-upstream-tag)

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

diff --git a/submodules/ubuntu-jammy b/submodules/ubuntu-jammy
index 161430c8f824bb25da5af96e433324c7bc3f1f73..f4c13e3c7e92851b6fb8b9aa7d1d61568628ca6d 160000 (submodule)
--- a/submodules/ubuntu-jammy
+++ b/submodules/ubuntu-jammy
@@ -1 +1 @@
-Subproject commit 161430c8f824bb25da5af96e433324c7bc3f1f73
+Subproject commit f4c13e3c7e92851b6fb8b9aa7d1d61568628ca6d