Correct designations for BA.2.87 after discussion with @AngieHinrichs

The previously designated sequences were from a branch that had an extra
mutation that isn't present in BA.2.87

The now designated sequences are the closest matches to BA.2.87,
due to having 18744T.

The very closest match is a singlet
hCoV-19/South_Africa/NCV977/2022|EPI_ISL_11674401|2022-02-21
which shares an extra C16575T with BA.2.87.1