build(contents): restrict included pkg contents

Author: codejedi365

package.json

@@ -3,9 +3,9 @@
   "version": "1.2.0",
   "description": "Extending the Jest default runner to run tests serially - useful for integration tests",
   "main": "index.js",
-  "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
-  },
+  "files": [
+    "index.js"
+  ],
   "repository": {
     "type": "git",
     "url": "git+https://github.com/gabrieli/jest-serial-runner.git"