### Describe the bug

The following test code in `AxiosHeaders.js`

```
  describe('clear', ()=> {
    it('should clear all headers', () => {
      const headers = new AxiosHeaders({x: 1, y:2});

      headers.clear();

      assert.notDeepStrictEqual(headers, {});
    });

    it('should clear matching headers if a matcher was specified', () => {
      const headers = new AxiosHeaders({foo: 1, 'x-foo': 2, bar: 3});

      assert.notDeepStrictEqual(headers, {foo: 1, 'x-foo': 2, bar: 3});

      headers.clear(/^x-/);

      assert.notDeepStrictEqual(headers, {foo: 1, bar: 3});
    });
  });
```

Doesn't fail if you remove the implementation for `headers.clear()`

### To Reproduce

Remove the following lines

```
  clear(matcher) {
    const keys = Object.keys(this);
    let i = keys.length;
    let deleted = false;

    while (i--) {
      const key = keys[i];
      if(!matcher || matchHeaderValue(this, this[key], key, matcher)) {
        delete this[key];
        deleted = true;
      }
    }

    return deleted;
  }
```

to 

```
  clear(matcher) {
    return true;
  }
```

### Code snippet

_No response_

### Expected behavior

Tests should fail

### Axios Version

_No response_

### Adapter Version

_No response_

### Browser

_No response_

### Browser Version

_No response_

### Node.js Version

_No response_

### OS

_No response_

### Additional Library Versions

_No response_

### Additional context/Screenshots

_No response_
test/unit/core/AxiosHeaders.js
});
      it('should support function', function () {
        const headers = new AxiosHeaders();
        headers.set('foo', 'bar=value1');
        assert.strictEqual(headers.get('foo', (value, header) => {
          assert.strictEqual(value, 'bar=value1');
          assert.strictEqual(header, 'foo');
          return value;
        }), 'bar=value1');
        assert.strictEqual(headers.get('foo', () => false), false);
      });
    });
  });
  describe('has', function () {
    it('should return true if the header is defined, otherwise false', function () {
      const headers = new AxiosHeaders();
      headers.set('foo', 'bar=value1');
      assert.strictEqual(headers.has('foo'), true);
      assert.strictEqual(headers.has('bar'), false);
    });
    describe('filter', function () {
      it('should support RegExp', function () {
        const headers = new AxiosHeaders();
        headers.set('foo', 'bar=value1');
        assert.strictEqual(headers.has('foo', /^bar=(\w+)/), true);
        assert.strictEqual(headers.has('foo', /^foo=/), false);
      });
      it('should support function', function () {
        const headers = new AxiosHeaders();
        headers.set('foo', 'bar=value1');