lowrankupdate / lowrankdowndate not defined for StaticArrays

lowrankupdate / lowrankdowndate are not defined for StaticArrays

```julia
AL = randn(SMatrix{4,4,ComplexF64})
A = AL'AL
A_chol = cholesky(Hermitian(A))
a = randn(SVector{4, ComplexF64}) / 100
lowrankdowndate(A_chol, a)
# ERROR: MethodError: no method matching lowrankdowndate(::Cholesky{ComplexF64, SMatrix{4, 4, ComplexF64, 16}}, ::SVector{4, ComplexF64})
```