adding methods to `promote_type` is not allowed

[nsajko]

You probably meant to add a method to promote_rule instead in each of these cases:

TropicalNumbers.jl/src/tropical_maxmul.jl

Lines 69 to 70 in f0deaa3

	# promotion rules
	Base.promote_type(::Type{TropicalMaxMul{T1}}, b::Type{TropicalMaxMul{T2}}) where {T1, T2} = TropicalMaxMul{promote_type(T1,T2)}

TropicalNumbers.jl/src/tropical_minplus.jl

Lines 75 to 76 in f0deaa3

	# promotion rules
	Base.promote_type(::Type{TropicalMinPlus{T1}}, b::Type{TropicalMinPlus{T2}}) where {T1, T2} = TropicalMinPlus{promote_type(T1,T2)}

TropicalNumbers.jl/src/tropical_maxplus.jl

Lines 82 to 83 in f0deaa3

	# promotion rules
	Base.promote_type(::Type{Tropical{T1}}, b::Type{Tropical{T2}}) where {T1, T2} = Tropical{promote_type(T1,T2)}

TropicalNumbers.jl/src/counting_tropical.jl

Line 65 in f0deaa3

Base.promote_type(::Type{CountingTropical{T1,CT1}}, b::Type{CountingTropical{T2,CT2}}) where {T1,T2,CT1,CT2} = CountingTropical{promote_type(T1,T2), promote_type(CT1,CT2)}

[GiggleLiu]

Thank you! Fixed in the above PR.