update to version 3.1.0
update to version 3.1.0

https://github.com/nlohmann/json/releases/tag/v3.1.0

- Release date: 2018-02-01
- SHA-256: d40f614d10a6e4e4e80dca9463da905285f20e93116c36d97d4dc1aa63d10ba4

FALCONN-LIB/FALCONN,FALCONN-LIB/FALCONN,FALCONN-LIB/FALCONN,FALCONN-LIB/FALCONN