fixing the typo

Co-authored-by: Anna Jaruga <ajaruga@caltech.edu>

parcel/Example_Frostenberg_Immersion_Freezing.jl

@@ -188,7 +188,7 @@ for (γ, color) in zip(γ_range, colors)
         push!(solutions, sol)
     end
     mean_sol = sum(solutions) / length(solutions)
-    plot_results(sol.t, sol, γ, "γ=", " s", :solid, color)
+    plot_results(sol.t, mean_sol, γ, "γ=", " s", :solid, color)
 end
 
 MK.save("frostenberg_immersion_freezing.svg", fig)