Clamp in ZonalWind to [0, 1] for sqrt

[milankl]

@simone-silvestri found a bug

julia> spectral_grid = SpectralGrid(trunc=119, Grid=FullClenshawGrid, dealiasing=2)
SpectralGrid:
├ Spectral:   T119 LowerTriangularMatrix{Complex{Float32}}, radius = 6.371e6 m
├ Grid:       179-ring FullClenshawGrid{Float32}, 64440 grid points
├ Resolution: 89km (average)
├ Vertical:   8-layer SigmaCoordinates
└ Device:     CPU using Array

julia> model = PrimitiveWetModel(spectral_grid)

julia> simulation = initialize!(model)
[ Info: Time step changed from 640000 to 600000 milliseconds (-6%) to match output frequency.
ERROR: DomainError with -2.4943467069604708e-8:
sqrt was called with a negative real argument but will only return a complex result if called with a complex argument. Try sqrt(Complex(x)).
Stacktrace:
 [1] throw_complex_domainerror(f::Symbol, x::Float64)
   @ Base.Math ./math.jl:33
 [2] sqrt
   @ ./math.jl:608 [inlined]
 [3] initialize!(progn::PrognosticVariables{…}, initial_conditions::ZonalWind, model::PrimitiveWetModel{…})
   @ SpeedyWeather ~/.julia/packages/SpeedyWeather/qwHr6/src/dynamics/initial_conditions.jl:293