fix prepare script

Author: tiagoschenkel

package.json

@@ -12,7 +12,7 @@
     "clean-up": "rimraf .nyc_output && rimraf coverage && rimraf lib && rimraf dev",
     "compile:src": "tsc -d",
     "compile:test": "tsc -p tsconfig.test.json -d",
-    "prepare": "npm run clean-up && compile:src",
+    "prepare": "npm run clean-up && npm run compile:src",
     "prepublishOnly": "publish-please guard",
     "publish-please": "npm run autoformat && npm run clean-up && npm run test && publish-please"
   },