fix Serialized type boundedness

src/base/types/Serialized.jl

@@ -12,6 +12,10 @@ internal model will be loaded on-demand by using any accessor, or by calling
 mutable struct Serialized{M} <: MetabolicModel where {M<:MetabolicModel}
     m::Maybe{M}
     filename::String
+
+    Serialized{T}(filename::String) where {T} = new{T}(nothing, filename)
+    Serialized(model::T, filename::String) where {T<:MetabolicModel} =
+        new{T}(model, filename)
 end
 
 function _on_precached(m::Serialized, f, args...)

src/base/utils/Serialized.jl

@@ -11,7 +11,7 @@ function serialize_model(
     filename::String,
 )::Serialized{MM} where {MM<:MetabolicModel}
     open(f -> serialize(f, model), filename, "w")
-    Serialized{MM}(nothing, filename)
+    Serialized{MM}(filename)
 end
 
 """