net/kea-devel: Welcome kea-devel, tracking the development branch

The kea 2.7.X branch tracks kea development. We are importing 2.7.6
here. The development branch includes many fixes not in the 2.6.X
(stable) branch such as LLVM 19 and boost 1.87 support.

Note that just like bind9, also developed by ISC (isc.org), even version
numbers, i.e. 2.6, are stable branch while odd numbered version numbers,
i.e. 2.7, are development branch.