build: Update known-good for 1.1.121 header

Change-Id: I227c133c69f5befb978b73ba9b5530a8ce2b1055
diff --git a/scripts/known_good.json b/scripts/known_good.json
index 2c4ef3a..28e94ea 100644
--- a/scripts/known_good.json
+++ b/scripts/known_good.json
@@ -6,7 +6,7 @@
       "sub_dir" : "Vulkan-Headers",
       "build_dir" : "Vulkan-Headers/build",
       "install_dir" : "Vulkan-Headers/build/install",
-      "commit" : "9eab96f40634c81ed53d54d2c9df126a445dfd56"
+      "commit" : "v1.1.121"
     }
   ],
   "install_names" : {