Update graph-cli/graph-ts to the latest versions (0.28.1, 0.26.0)

Author: evaporei

package.json

@@ -13,8 +13,8 @@
     "deploy-local": "graph deploy example --ipfs http://127.0.0.1:5001 --node http://127.0.0.1:8020"
   },
   "devDependencies": {
-    "@graphprotocol/graph-cli": "^0.23.2",
-    "@graphprotocol/graph-ts": "^0.23.1"
+    "@graphprotocol/graph-cli": "^0.28.1",
+    "@graphprotocol/graph-ts": "^0.26.0"
   },
   "dependencies": {
     "babel-polyfill": "^6.26.0",