fix: fix publish failed due to git add command (#4)

Author: laggage

package.json

@@ -17,7 +17,7 @@
     "browser": "browserify index.js -t [ babelify --presets [ @babel/preset-env ] ] --standalone markdown-it-attrs -o markdown-it-attrs.browser.js",
     "coverage": "nyc report --reporter=text-lcov | coveralls",
     "lint": "eslint .",
-    "preversion": "mocha && npm run browser && git add markdown-it-attrs.browser.js",
+    "preversion": "mocha && npm run browser",
     "test": "npm run lint && nyc mocha"
   },
   "homepage": "https://github.com/arve0/markdown-it-attrs",