add popper.js

package.json

@@ -12,6 +12,7 @@
     "@babel/core": "^7.12.16",
     "@babel/preset-env": "^7.12.16",
     "@fortawesome/fontawesome-free": "^5.15.2",
+    "@popperjs/core": "^2.7.0",
     "admin-lte": "^3.0.5",
     "babel-loader": "^8.2.2",
     "css-loader": "^5.0.2",