chore: added typescript dep

Author: schickling

package.json

@@ -8,7 +8,7 @@
     "schema"
   ],
   "scripts": {
-    "prepublish": "npm run build",
+    "prepare": "npm run build",
     "build": "rm -rf dist && tsc -d",
     "test": "echo No tests yet"
   },
@@ -22,7 +22,8 @@
   },
   "devDependencies": {
     "@types/graphql": "^0.11.7",
-    "@types/node": "^8.5.2"
+    "@types/node": "^8.5.2",
+    "typescript": "^2.6.2"
   },
   "repository": {
     "type": "git",