fix eslint script

Author: mkg0

package.json

@@ -9,7 +9,7 @@
     "build": "NODE_ENV=production & yarn build-library & yarn build-demo",
     "build-demo": "webpack -p",
     "build-library": "babel ./src --out-dir ./dist --ignore test.js & postcss 'src/styles.css' -d dist & postcss 'src/theme/*.css' -d 'dist/theme'",
-    "lint": "eslint '**/*.js'",
+    "lint": "eslint 'src/**/*.js'",
     "test": "jest"
   },
   "keywords": [