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

[armijnhemel]

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"
            }
          ],