Update kusama stash for Khastor

Updated the kusama stash to match the change in kusama.json, as the participant requested.

Author: michalisFr

candidates/polkadot.json

@@ -870,7 +870,7 @@
       "slotId": 107,
       "name": "Khastor-PVN01",
       "stash": "1429tQ2RK8xCwiVYYw7YVUFGX2rbASQN2maMExay7x18neoZ",
-      "kusamaStash": "D6NNbc18fTh4WVQtmrTyLRHGv8SKVtjKFY8uV34k5ydBMaV",
+      "kusamaStash": "H4F8kJeJ8anTS1WUZATDaj6WfYzoxCvARaDFzQkN6pKzvvV",
       "riotHandle": "@khastor:matrix.org",
       "kyc": false
     },