Add license file

5 jobs for master in 17 minutes and 48 seconds (queued for 10 minutes and 56 seconds)
Status Name Job ID Coverage
  Test
passed debian:10 clang-7-libcpp-17 #21519

00:03:49

passed debian:10 gcc-7-17 #21518

00:04:36

passed debian:10 gcc-8-noassert-17 #21517

00:04:47

passed debian:11 gcc-9-20 #21516

00:04:30

passed ubuntu:18.04 clang-6-17 #21520

00:03:40