This target is not popular among active developers.
If nobody is using the testing kernel, this phase is pointless.
Switch this niche target to kernel 6.18 for testing.
Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/22680
Signed-off-by: Linus Walleij <linusw@kernel.org>