(@v1.7) pkg> activate --temp
  Activating new project at `/tmp/jl_u6D0ay`

(jl_u6D0ay) pkg> add ColorTypes@0.11.1 Colors
...

julia> using Colors

julia> Gray{Float32}(rand(RGB))
ERROR: MethodError: Cannot `convert` an object of type RGB{Float64} to an object of type Float32
Closest candidates are:
  convert(::Type{T}, ::T) where T<:Number at ~/packages/julias/julia-1.7/share/julia/base/number.jl:6
  convert(::Type{T}, ::Number) where T<:Number at ~/packages/julias/julia-1.7/share/julia/base/number.jl:7
  convert(::Type{T}, ::Base.TwicePrecision) where T<:Number at ~/packages/julias/julia-1.7/share/julia/base/twiceprecision.jl:262
  ...
Stacktrace:
 [1] Gray{Float32}(val::RGB{Float64})
   @ ColorTypes ~/.julia/packages/ColorTypes/LWFPo/src/types.jl:345
 [2] top-level scope
   @ REPL[7]:1