"SPDX-License-Identifier: Artistic-1.0+" not recognised

### Description

In a PHP source file, I have the following line:
```
* SPDX-License-Identifier: Artistic-1.0+
```

This results in:
```
LicenseInfoInFile: LicenseRef-scancode-unknown-spdx
```
and
```
LicenseID: LicenseRef-scancode-unknown-spdx
LicenseName: Unknown SPDX license detected but not recognized
LicenseComment: See details at https://github.com/nexB/scancode-toolkit/blob/develop/src/licensedcode/data/licenses/unknown-spdx.yml

ExtractedText: * SPDX-License-Identifier: Artistic-1.0+
```

I would have expected:
```
LicenseInfoInFile: Artistic-1.0+
```

Moreover, the URL https://github.com/nexB/scancode-toolkit/blob/develop/src/licensedcode/data/licenses/unknown-spdx.yml give a 404 error.

### How To Reproduce

```
svn checkout https://svn.code.sf.net/p/phpwiki/code/trunk phpwiki
```

```
./scancode -c -l -i --license-text --spdx-tv phpwiki.spdx phpwiki
```

Resulting SPDX file:

[phpwiki.spdx.txt](https://github.com/nexB/scancode-toolkit/files/10745540/phpwiki.spdx.txt)

### System configuration

```
./scancode --version
ScanCode version: 32.0.0rc1
ScanCode Output Format version: 3.0.0
SPDX License list version: 3.19
```
Ubuntu 22.10