Unity unit test library should be updated to a newer version
With newer versions of Unity, the build fails:
$ make
[...]
CC build/posix/external/unity/extras/fixture/src/unity_fixture.o
In Datei, eingebunden von external/unity/extras/fixture/src/unity_fixture.c:8:
external/unity/extras/fixture/src/unity_fixture.h:16:10: schwerwiegender Fehler: unity_memory.h: Datei oder Verzeichnis nicht gefunden
16 | #include "unity_memory.h"
| ^~~~~~~~~~~~~~~~
Kompilierung beendet.
[...]