URLs are not serialized according to WHATWG spec and compare differently

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### Describe the bug

Looking at the WHATWG example for [URL equality](https://url.spec.whatwg.org/#url-equivalence), the URLs `web+demo:/.//not-a-host/` and `web+demo:/path/..//not-a-host/` should be considered equal after [URL serialization](https://url.spec.whatwg.org/#url-serializing). When parsing those URLs using [ada](https://github.com/ada-url/ada), they are indeed serialized identically.

### To Reproduce

Using yarl 1.12.1, run
```python
import yarl
assert yarl.URL("web+demo:/path/..//not-a-host/") == yarl.URL("web+demo:/.//not-a-host/")
```

### Expected behavior

Both URLs should be serialized as described in the [WHATWG specification](https://url.spec.whatwg.org/#concept-url-serializer), i.e. the serialized result should be `web+demo:/.//not-a-host/` in both cases.

### Logs/tracebacks

```python-traceback
n/a
```

### Python Version

```console
Python 3.12.6
```

### multidict Version

```console
Name: multidict
Version: 6.1.0
```

### yarl Version

```console
Name: yarl
Version: 1.12.1
```

### OS

Linux

### Additional context

_No response_