companion: set allowed http methods internally

packages/@uppy/companion/src/companion.js

@@ -62,6 +62,7 @@ module.exports.app = (options = {}) => {
   app.use(interceptGrantErrorResponse)
   app.use(new Grant(grantConfig))
   app.use((req, res, next) => {
+    res.header('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, DELETE')
     res.header(
       'Access-Control-Allow-Headers',
       [