[keps] Changes AMSAT-NA TLE Distribution for May 9, 2019

The following amateur satellites have decayed and have been removed from the AMSAT-NA TLE distribution: PHOENIX - CAT ID 42706 (reentered 05-08-2019). BIRD-J - CAT ID 42820 (reentered 05-03-2019). BIRD-B - CAT ID 42823 (reentered 05-06-2019).