Add selftests/sched_ext files to build artifacts

.github/scripts/tar-artifact.sh

@@ -81,12 +81,12 @@ if [ $archive_make_helpers -ne 0 ]; then
   additional_file_list+=(
     "scripts/"
     "tools/testing/selftests/bpf/"
+    "tools/testing/selftests/sched_ext/"
     "tools/include/"
     "tools/bpf/bpftool/"
   )
 fi
 
-
 tar -cf - \
     kbuild-output \
     "${additional_file_list[@]}" \
@@ -95,6 +95,7 @@ tar -cf - \
     --exclude '*.h'                    \
     --exclude '*.output'               \
     selftests/bpf/                     \
+    selftests/sched_ext/               \
   | zstd -T0 -19 -o "vmlinux-${arch}-${toolchain}.tar.zst"
 
 # Cleanup and restore the original KBUILD_OUTPUT