Add missing dependecy

web/package.json

@@ -17,6 +17,7 @@
     "@types/dotenv": "^6.1.1",
     "@types/express": "^4.17.0",
     "@types/request-promise-native": "^1.0.16",
+    "autoprefixer": "^9.6.1",
     "btoa": "^1.2.1",
     "bulma": "^0.7.5",
     "compression": "^1.7.1",