<!-- Click "Preview" for a more readable version --

Please read and follow the instructions before submitting an issue:

- Read all our documentation, especially the [README](https://github.com/axios/axios/blob/master/README.md). It may contain information that helps you solve your issue.
- Ensure your issue isn't already [reported](https://github.com/axios/axios/issues?utf8=%E2%9C%93&q=is%3Aissue).
- If you aren't sure that the issue is caused by Axios or you just need help, please use [Stack Overflow](https://stackoverflow.com/questions/tagged/axios) or [our chat](https://gitter.im/mzabriskie/axios).
- If you're reporting a bug, ensure it isn't already fixed in the latest Axios version.
- Don't remove any title of the issue template, or it will be treated as invalid by the bot.

⚠️👆 Feel free to these instructions before submitting the issue 👆⚠️
-->

#### Describe the issue
Passing Uint8Array or Buffer to postForm results in "source.on is not a function" exception.

#### Example Code
```js
const data = Uint8Array.from([1, 2, 3])
axios.postForm('http://some.url', { data })

// or

const data = Uint8Array.from([1, 2, 3])
axios.postForm('http://some.url', { data: Buffer.from(data) })
```

#### Expected behavior, if applicable
axios should POST a field "data" with the content of the Uint8Array / Buffer

#### Environment
 - Axios Version 0.27.2
 - Node.js Version 18.2.0
 - OS: Windows 11

#### Additional context/Screenshots
Code is compiled from TypeScript using typescript 4.6.4 and a tsconfig.json that extends @tsconfig/node18/tsconfig.json

I am trying to upload the PDF output of puppeteer.


What am I doing wrong?
test/unit/adapters/http.js
}).then(function (res) {
          var base64 = Buffer.from('user:pass', 'utf8').toString('base64');
          assert.equal(res.data, 'Basic ' + base64, 'should authenticate to the proxy');
          done();
        }).catch(done);
      });
    });
  });
  it('should support proxy auth from env', function (done) {
    server = http.createServer(function (req, res) {
      res.end();
    }).listen(4444, function () {
      proxy = http.createServer(function (request, response) {
        var parsed = url.parse(request.url);
        var opts = {
          host: parsed.hostname,
          port: parsed.port,
          path: parsed.path
        };
        var proxyAuth = request.headers['proxy-authorization'];
        http.get(opts, function (res) {
          var body = '';
          res.on('data', function (data) {
            body += data;
          });
          res.on('end', function () {
            response.setHeader('Content-Type', 'text/html; charset=UTF-8');
            response.end(proxyAuth);
          });
        });