fix: address method ambiguity

Author: ReubenJ

src/qualitative_networks.jl

@@ -460,8 +460,10 @@ end
 function JSON.json(qn::QualitativeNetwork)
     return JSON.json(qn_to_bma_dict(qn); omit_empty = false)
 end
-JSON.json(io_or_filename, qn::QualitativeNetwork) =
+JSON.json(io_or_filename, qn::T) where {T<:QualitativeNetwork} =
     JSON.json(io_or_filename, qn_to_bma_dict(qn); omit_empty = false)
+JSON.json(io::IO, qn::T) where {T<:QualitativeNetwork} =
+    JSON.json(io, qn_to_bma_dict(qn); omit_empty = false)
 
 """
     $(TYPEDSIGNATURES)