Add rule for Base.unsafe_trunc

This is to match `Base.trunc` and notably is used in
`convert(::Type{Int64}, ::Float64)`

Author: topolarity

src/rulesets/Base/nondiff.jl

@@ -445,6 +445,7 @@ end
 @non_differentiable unique(::AbstractArray{Symbol})
 @non_differentiable unmark(::IO)
 @non_differentiable unsafe_string(::Cstring)
+@non_differentiable unsafe_trunc(::Any...)
 @non_differentiable uppercase(::AbstractString)
 @non_differentiable uppercase(::AbstractChar)
 @non_differentiable uppercasefirst(::AbstractString)