package/json-for-modern-cpp: bump to version 3.12.0
- Release Notes: https://github.com/nlohmann/json/releases/tag/v3.12.0
- updated LICENSE.MIT hash due to updated year
Signed-off-by: Michael Nosthoff <buildroot@heine.tech>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>