Update Eigen to commit:21e89b930c6af56dbdaeea2a91d8b9d6fd2c208a

CHANGELOG
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21e89b930 - Enable default behavior for pmin<PropagateFast>, predux_min, etc
4fdf87bbf - clean up intel packet reductions
a7f183cad - Add factory/getters for quat coeffs in both orders
d81aa18f4 - Explicitly construct the scalar for non-implicitly convertible types

PiperOrigin-RevId: 766811637
Change-Id: I6184e3c71bb418f61715e8c3d5fb29d357749417
12 files changed