8.0.0

CHANGES:

• TCP: add ID for PCB for connection tracking (#495 @TheLortex)

• Unix stack, UDP: copy buffer before passing it to client (#502 @reynir)

• API renamings (due to ppx_cstruct removal): accessors such as
  Icmpv4_wire.get_icmpv4_ty are now Icmpv4_wire.get_ty ("_icmpv4" is removed)
  (#505)

• Use Cstruct.to_string instead of deprecated Cstruct.copy (#506 @hannesm)

• Remove ppx_cstruct dependency (#505 @hannesm)

• Remove mirage-profile dependency (#504 @hannesm)

• Remove Mirage3 cross-compilation runes (#507 @hannesm)

• opam: add lower bounds for cmdliner and alcotest (#506 @hannesm)