net/kea-devel: prepare for Boost-1.90 (+)

Ensure logger always have #include <boost/static_assert.hpp>

c++ -Isrc/lib/log/libkea-log.so.85.0.0.p -Isrc/lib/log -I../src/lib/log -I. -I.. -Isrc -I../src -Isrc/bin -I../src/bin -Isrc/lib -I../src/lib -I/usr/local/include -fdiagnostics-color=never -D_LIBCPP_HAR
../src/lib/log/logger_level_impl.cc:47:5: error: use of undeclared identifier 'BOOST_STATIC_ASSERT'

47 |     BOOST_STATIC_ASSERT(static_cast<int>(DEFAULT) == 0);
   |     ^

../src/lib/log/logger_level_impl.cc:48:5: error: use of undeclared identifier 'BOOST_STATIC_ASSERT'

48 |     BOOST_STATIC_ASSERT(static_cast<int>(DEBUG) == 1);
   |     ^

../src/lib/log/logger_level_impl.cc:49:5: error: use of undeclared identifier 'BOOST_STATIC_ASSERT'

49 |     BOOST_STATIC_ASSERT(static_cast<int>(INFO) == 2);
   |     ^

../src/lib/log/logger_level_impl.cc:50:5: error: use of undeclared identifier 'BOOST_STATIC_ASSERT'

50 |     BOOST_STATIC_ASSERT(static_cast<int>(WARN) == 3);
   |     ^

../src/lib/log/logger_level_impl.cc:51:5: error: use of undeclared identifier 'BOOST_STATIC_ASSERT'

51 |     BOOST_STATIC_ASSERT(static_cast<int>(ERROR) == 4);
   |     ^

../src/lib/log/logger_level_impl.cc:52:5: error: use of undeclared identifier 'BOOST_STATIC_ASSERT'

52 |     BOOST_STATIC_ASSERT(static_cast<int>(FATAL) == 5);
   |     ^

../src/lib/log/logger_level_impl.cc:53:5: error: use of undeclared identifier 'BOOST_STATIC_ASSERT'

53 |     BOOST_STATIC_ASSERT(static_cast<int>(NONE) == 6);
   |     ^

7 errors generated.