Remove deprecated bindings RGB4 RGB1

[dgleich]

This removes the deprecated bindings for RGB4 and RGB1, see discussion:

JuliaIO/ImageMagick.jl#235
and similar fix in ColorTypes.jl
JuliaGraphics/ColorTypes.jl#312

It also requires the new version of ColorTypes in Compat, but that will cause failures until that version is registered.

CC: @ViralBShah, @ararslan

[ViralBShah]

ColorTypes.jl registration PR: JuliaRegistries/General#117694

Let's re-run the CI in an hour or so.

[ViralBShah]

There is an ambiguity test failing:

     Testing Running tests...
Test Failed at /home/runner/work/Colors.jl/Colors.jl/test/runtests.jl:2
  Expression: isempty(detect_ambiguities(Colors))
   Evaluated: isempty(Tuple{Method, Method}[(_convert(::Type{Cout}, ::Type{C1}, ::Type{C1}, c) where {Cout<:Color, C1<:Color} @ ColorTypes ~/.julia/packages/ColorTypes/0RO5O/src/conversions.jl:90, _convert(::Type{Cdest}, ::Type{Odest}, ::Type{Osrc}, g) where {Cdest<:Color, Odest, Osrc<:AbstractGray} @ Colors ~/work/Colors.jl/Colors.jl/src/conversions.jl:75)])

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.48%. Comparing base (f0a508b) to head (12253dc).
Report is 9 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (f0a508b) and HEAD (12253dc). Click for more details.

HEAD has 34 uploads less than BASE

Flag	BASE (f0a508b)	HEAD (12253dc)
	37	3

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #557       +/-   ##
===========================================
- Coverage   98.82%   87.48%   -11.35%     
===========================================
  Files          10        9        -1     
  Lines        1281      831      -450     
===========================================
- Hits         1266      727      -539     
- Misses         15      104       +89     

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[ViralBShah]

Commenting out the ambiguity test, everything else runs fine.