Preserve Checkpoint across update installs.

Skip deleting sd:/switch/checkpoint so user saves under saves/ are not wiped.

source/deletion_lists_update.h

@@ -136,7 +136,6 @@ static const char* switch_dirs_to_delete[] = {
     "sd:/switch/AtmoXL-Titel-Installer",
     "sd:/switch/Benchmark-Toolbox",
     "sd:/switch/breeze",
-    "sd:/switch/checkpoint",
     "sd:/switch/cheats-updater",
     "sd:/switch/chiaki",
     "sd:/switch/ChoiDujourNX",