ci(apply-kernel-branding): fix conditional syntax in bash script

.github/actions/apply-kernel-branding/action.yml

@@ -29,7 +29,7 @@ runs:
         if [ "${{ inputs.variant }}" = "Wild" ]; then
           tac scripts/setlocalversion | awk '!seen && /^echo / {seen=1; next} 1' | tac > scripts/setlocalversion.tmp
           mv scripts/setlocalversion.tmp scripts/setlocalversion
-          if [ ${{ inputs.kernel_version }} == "6.6" || ${{ inputs.kernel_version }} == "6.12" ]; then
+          if [[ ${{ inputs.kernel_version }} == "6.6" || ${{ inputs.kernel_version }} == "6.12" ]]; then
             KERNEL_STRING="${{ inputs.kernel_version }}.${{ inputs.sublevel }}"
             echo "echo \"$KERNEL_STRING-Wild\"" >> scripts/setlocalversion
           else