loads: OverflowError while decoding too big escaped Unicode character

```python
pyjson5.loads(r'{\U11111111: 2}')
```

> File src/_decoder.pyx:509, in pyjson5.pyjson5._decode_identifier_name()
> 
> File src/_decoder.pyx:113, in pyjson5.pyjson5._get_hex_character()
> 
> File src/_raise_decoder.pyx:39, in pyjson5.pyjson5._raise_expected_s()
> 
> OverflowError: %c arg not in range(0x110000)

Should raise a `Json5DecoderException` instead