### Describe the bug

Relying on axios automatic serialization to create a form-data results in this error. The following lines are responsible of this error : https://github.com/axios/axios/blob/release/dist/node/axios.cjs#L2654 (mainly the `getLengthSync` function)

According to [form-data themselves](https://github.com/form-data/form-data), using `getLengthSync` is [not recommended](https://github.com/form-data/form-data/blob/master/Readme.md?plain=1#L350).

### To Reproduce

- Create a file buffer with `fs.createReadStream`
- Set HTTP header `Content-Type` to `multipart/form-data` to make use of [automatic serialization](https://github.com/axios/axios#-automatic-serialization-to-formdata)
- Get the form-data `Cannot calculate proper length in synchronous way.` error

### Code snippet

```js
const axios = require("axios");
const fs = require("node:fs");
const fileBuffer = fs.createReadStream("./file.ext");

axios.post('https://httpbin.org/post', {file: fileBuffer}, {
  headers: {
    'Content-Type': 'multipart/form-data'
  }
})
.then(({data}) => console.log(data))
.catch((err) => console.error(err));
```


### Expected behavior

The content length should be calculated without throwing any error.

### Axios Version

1.3.0

### Adapter Version

_No response_

### Browser

_No response_

### Browser Version

_No response_

### Node.js Version

16.19.0

### OS

_No response_

### Additional Library Versions

_No response_

### Additional context/Screenshots

_No response_
lib/core/AxiosHeaders.js
const self = this;
    const headers = {};
    utils.forEach(this, (value, header) => {
      const key = utils.findKey(headers, header);
      if (key) {
        self[key] = normalizeValue(value);
        delete self[header];
        return;
      }
      const normalized = format ? formatHeader(header) : String(header).trim();
      if (normalized !== header) {
        delete self[header];
      }
      self[normalized] = normalizeValue(value);
      headers[normalized] = true;
    });
    return this;
  }
  concat(...targets) {