Update ubuntu/firewall kernel to 6.12.18 (#287)

Author: majst01

debian/docker-make.ubuntu.yaml

@@ -13,7 +13,7 @@ default-build-args:
   - DOCKER_APT_CHANNEL=noble
   - CRI_VERSION=v1.32.0
   # see https://kernel.ubuntu.com/mainline for available versions
-  - UBUNTU_MAINLINE_KERNEL_VERSION=v6.12.16
+  - UBUNTU_MAINLINE_KERNEL_VERSION=v6.12.18
   - ICE_VERSION=1.14.13
   - ICE_PKG_VERSION=1.3.36.0