wrong detection: AGPL-3.0-only instead of GPL-3.0-or-later

### Description

https://github.com/GNOME/gimp/blob/master/app/widgets/gimpdashboard.h

clearly contains a gpl 3 or later:

```
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
```
but scancode says it is agpl 3.0 only:

```
"matches": [
{
"license_expression": "agpl-3.0",
"license_expression_spdx": "AGPL-3.0-only",
"from_file": "gimp/app/widgets/gimpdashboard.h",
"start_line": 1,
"end_line": 18,
"matcher": "3-seq",
"score": 88.03,
"matched_length": 103,
"match_coverage": 88.03,
"rule_relevance": 100,
"rule_identifier": "agpl-3.0_326.RULE",
"rule_url": "https://github.com/nexB/scancode-toolkit/tree/develop/src/licensedcode/data/rules/agpl-3.0_326.RULE"
}
],

```