Fix bug in show of hartree with scaling factor (#926)

Author: ClementineBarat

src/terms/hartree.jl

@@ -17,7 +17,7 @@ end
 Hartree(; scaling_factor=1) = Hartree(scaling_factor)
 (hartree::Hartree)(basis)   = TermHartree(basis, hartree.scaling_factor)
 function Base.show(io::IO, hartree::Hartree)
-    fac = isone(hartree.scaling_factor) ? "" : ", scaling_factor=$scaling_factor"
+    fac = isone(hartree.scaling_factor) ? "" : ", scaling_factor=$(hartree.scaling_factor)"
     print(io, "Hartree($fac)")
 end