system/gnu-unifont: Updated for version 13.0.03.

Performed the following checks:

1. Download locations:

• https://ftpmirror.gnu.org/unifont/unifont-13.0.03/unifont-13.0.03.tar.gz
• https://ftp.gnu.org/gnu/unifont/unifont-13.0.03/unifont-13.0.03.tar.gz
• ftp://ftp.gnu.org/gnu/unifont/unifont-13.0.03/unifont-13.0.03.tar.gz
• http://unifoundry.com/pub/unifont/unifont-13.0.03/unifont-13.0.03.tar.gz

Size:   23095978 bytes
MD5:    ea585627fce8b5d798161403fbfaef06
SHA256: 071e2ca005d97d72e79b8cb68df886f1f730cb5f0e7739a4c6e8d068ded28212

2. Verified download signature.

3. Scanned download using ClamAV with latest virus databases.

4. Scanned download using VirusTotal:

https://www.virustotal.com/gui/url/7d2302dd89569ab641b39a0b999c01e05c112999e6cf4c541d0f829ecfcbb7de/details