`Vararg` deprecation warnings

During precompilation ``` ┌ QuantumOpticsBase │ WARNING: Wrapping `Vararg` directly in UnionAll is deprecated (wrap the tuple instead). │ You may need to write `f(x::Vararg{T})` rather than `f(x::Vararg{<:T})` or `f(x::Vararg{T}) where ```