These PNG files were using an indexed color palette, which is currently not supported, although most image optimizer tools will try to use it if possible.
Closes#7121.
Update the country codes which are displayed for the flags in the UI. This only changes the names which are displayed in the UI but not how flags are communicated between server and client.
- Use ISO 3166-2 subdivision codes:
- England: XEN → GB-ENG
- Northern Ireland: XNI → GB-NIR
- Scotland: XSC → GB-SCT
- Wales: XWA → GB-WLS
- Catalonia: XCA → ES-CT
- Galicia: XGL → ES-GA
- Use ISO 3166/MA exceptional reservation code:
- European Union: XEU → EU
- Move South Sudan (SS) to official codes, as it was officially assigned in the year 2011.
Closes#7071.
4740: Update French flag (fixes#4738) r=Jupeyy a=def-
by Nouaa
Blue color was changed recently
<!-- What is the motivation for the changes of this pull request -->
## Checklist
- [x] Tested the change ingame
- [ ] Provided screenshots if it is a visual change
- [ ] Tested in combination with possibly related configuration options
- [ ] Written a unit test if it works standalone, system.c especially
- [ ] Considered possible null pointers and out of bounds array indexing
- [ ] Changed no physics that affect existing maps
- [ ] Tested the change with [ASan+UBSan or valgrind's memcheck](https://github.com/ddnet/ddnet/#using-addresssanitizer--undefinedbehavioursanitizer-or-valgrinds-memcheck) (optional)
Co-authored-by: def <dennis@felsin9.de>