`hash(::Quaternion, ::UInt)` should be defined

[hyrodium]

The following behavior is not consistent, and can be fixed by adding hash(::Quaternion, ::UInt) method.

julia> using Quaternions

julia> isequal(1, complex(1))
true

julia> 1 |> hash
0x5bca7c69b794f8ce

julia> complex(1) |> hash
0x5bca7c69b794f8ce

julia> isequal(1, quat(1))  # isequal(a,b) == true should imply `hash(a) == hash(b)`
true

julia> quat(1) |> hash
0x37cb992a8d339608

julia> unique(Complex[complex(2), complex(big"2")])
1-element Vector{Complex}:
 2 + 0im

julia> unique(Quaternion[quat(2), quat(big"2")])
2-element Vector{Quaternion}:
  Quaternion{Int64}(2, 0, 0, 0)
 Quaternion{BigInt}(2, 0, 0, 0)

x-ref: https://github.com/JuliaGeometry/Quaternions.jl/pull/121#issue-1488451695