### Describe the issue

I set `axios.defaults.headers.common['Content-Type'] = 'application/json'`. When firing a `axios.patch` request (without a config), the request uses `application/x-www-form-urlencoded` instead.

### Example Code

```js
// This does not work as expected:
axios.defaults.headers.common['Content-Type'] = 'application/json'

// This does:
axios.defaults.headers.common['Content-Type'] = 'application/json'
axios.defaults.headers.patch['Content-Type'] = 'application/json'
```


### Expected behavior

I expected POST requests to use `axios.defaults.headers.common`, too.

I think this is where the problem (or intended behaviour) comes from: https://github.com/axios/axios/blob/3f53eb6960f05a1f88409c4b731a40de595cb825/lib/core/dispatchRequest.js#L46

### Axios Version

1.4.0

### Adapter Version

_No response_

### Browser

Firefox

### Browser Version

116.0.3 (64-bit)

### Node.js Version

_No response_

### OS

_No response_

### Additional Library Versions

_No response_

### Additional context/Screenshots

_No response_
test/specs/defaults.spec.js
});
  it('should use request config', function (done) {
    axios('/foo', {
      baseURL: 'http://www.example.com'
    });
    getAjaxRequest().then(function (request) {
      expect(request.url).toBe('http://www.example.com/foo');
      done();
    });
  });
  it('should use default config for custom instance', function (done) {
    const instance = axios.create({
      xsrfCookieName: XSRF_COOKIE_NAME,
      xsrfHeaderName: 'X-CUSTOM-XSRF-TOKEN'
    });
    document.cookie = instance.defaults.xsrfCookieName + '=foobarbaz';
    instance.get('/foo');
    getAjaxRequest().then(function (request) {
      expect(request.requestHeaders[instance.defaults.xsrfHeaderName]).toEqual('foobarbaz');
      done();
    });
  });
  it('should use GET headers', function (done) {
    axios.defaults.headers.get['X-CUSTOM-HEADER'] = 'foo';
    axios.get('/foo');
    getAjaxRequest().then(function (request) {
      expect(request.requestHeaders['X-CUSTOM-HEADER']).toBe('foo');
      done();
    });
  });