build(deps): bump formidable from 2.1.2 to 3.5.0 in /src (#5796)

* build(deps): bump formidable from 2.1.2 to 3.5.0 in /src

Bumps [formidable](https://github.com/node-formidable/formidable) from 2.1.2 to 3.5.0.
- [Release notes](https://github.com/node-formidable/formidable/releases)
- [Changelog](https://github.com/node-formidable/formidable/blob/master/CHANGELOG.md)
- [Commits](https://github.com/node-formidable/formidable/commits/v3.5.0)

---
updated-dependencies:
- dependency-name: formidable
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

* formidable migration

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: John McLear <john@mclear.co.uk>

src/node/hooks/express/apicalls.js

@@ -8,20 +8,19 @@ const util = require('util');
 
 exports.expressPreSession = async (hookName, {app}) => {
   // The Etherpad client side sends information about how a disconnect happened
-  app.post('/ep/pad/connection-diagnostic-info', (req, res) => {
-    new Formidable().parse(req, (err, fields, files) => {
-      clientLogger.info(`DIAGNOSTIC-INFO: ${fields.diagnosticInfo}`);
-      res.end('OK');
-    });
+  app.post('/ep/pad/connection-diagnostic-info', async (req, res) => {
+    const [fields, files] = await (new Formidable({})).parse(req);
+    clientLogger.info(`DIAGNOSTIC-INFO: ${fields.diagnosticInfo}`);
+    res.end('OK');
   });
 
-  const parseJserrorForm = async (req) => await new Promise((resolve, reject) => {
+  const parseJserrorForm = async (req) => {
     const form = new Formidable({
       maxFileSize: 1, // Files are not expected. Not sure if 0 means unlimited, so 1 is used.
     });
-    form.on('error', (err) => reject(err));
-    form.parse(req, (err, fields) => err != null ? reject(err) : resolve(fields.errorInfo));
-  });
+    const [fields, files] = await form.parse(req);
+    return fields.errorInfo;
+  };
 
   // The Etherpad client side sends information about client side javscript errors
   app.post('/jserror', (req, res, next) => {

src/node/hooks/express/openapi.js

@@ -15,8 +15,7 @@
  */
 
 const OpenAPIBackend = require('openapi-backend').default;
-const formidable = require('formidable');
-const {promisify} = require('util');
+const IncomingForm = require('formidable').IncomingForm;
 const cloneDeep = require('lodash.clonedeep');
 const createHTTPError = require('http-errors');
 
@@ -596,9 +595,13 @@ exports.expressPreSession = async (hookName, {app}) => {
           // read form data if method was POST
           let formData = {};
           if (c.request.method === 'post') {
-            const form = new formidable.IncomingForm();
-            const parseForm = promisify(form.parse).bind(form);
-            formData = await parseForm(req);
+            const form = new IncomingForm();
+            formData = (await form.parse(req))[0];
+            for (const k of Object.keys(formData)) {
+              if (formData[k] instanceof Array) {
+                formData[k] = formData[k][0];
+              }
+            }
           }
 
           const fields = Object.assign({}, header, params, query, formData);