fix(ci/mainline): Bump to 6.18-rc7

Signed-off-by: Loïc Minier <[email protected]>

Author: lool

.github/workflows/linux.yml

@@ -100,7 +100,7 @@ jobs:
     uses: ./.github/workflows/debos.yml
     with:
       mainline_kernel: true
-      kernelpackage: linux-image-6.18.0-rc6
+      kernelpackage: linux-image-6.18.0-rc7
 
   test-mainline-linux:
     uses: ./.github/workflows/lava-test.yml