Incomplete copyright detection for regular name

### Description

Seemingly regular copyright holders are not detected correctly.

### How To Reproduce

* `wget https://raw.githubusercontent.com/arthurdejong/python-stdnum/52d316200c347b4f3d2b61a77ce746f3d28a3815/stdnum/eu/ecnumber.py`
* `scancode --copyright --json-pp out ecnumber.py`

We get

```json
{
"path": "ecnumber.py",
"type": "file",
"copyrights": [
{
"copyright": "Copyright (c) 2023 Daniel",
"start_line": 3,
"end_line": 3
}
],
"holders": [
{
"holder": "Daniel",
"start_line": 3,
"end_line": 3
}
],
"authors": [],
"scan_errors": []
}
```

instead of the full `Copyright (c) 2023 Daniel Weber`.

### System configuration

* What OS are you running on? Linux
* What version of scancode-toolkit was used to generate the scan file? 32.5.0
* What installation method was used to install/run scancode? pip