Pin libc subdependency for MSRV 1.59.0 and allow successor to Unicode DFS license

[sirhcel]

• The libc crate bumped MSRV from 1.19.0 to 1.63.0 with patch release 0.2.164
  • This breaks our builds (like run 12104758738) as we are still using MSRV 1.59.0
  • Adding a direct dependency to massage the dependency resolver into using a compatible version already did the trick with Pin sub-dependecy of clap to be compatible with MSRV #186
• In addition the license of the sub dependency unicode-ident got updated
  • We allowed the Unicode DFS license
  • Unicode 3.0 is a successor to Unicode DFS

[eldruin]

Thank you!