Relax Fill return type in mvlognormal tests (#1890)

* Relax Fill return type in mvlognormal tests

* Use AbstractFill instead of Union

Co-authored-by: David Widmann <[email protected]>

---------

Co-authored-by: David Widmann <[email protected]>

Author: jishnub

test/multivariate/mvlognormal.jl

@@ -19,7 +19,7 @@ function test_mvlognormal(g::MvLogNormal, n_tsamples::Int=10^6,
     @test partype(g) == Float64
     @test isa(mn, Vector{Float64})
     if g.normal.μ isa Zeros{Float64,1}
-        @test md isa Fill{Float64,1}
+        @test md isa FillArrays.AbstractFill{Float64,1}
     else
         @test md isa Vector{Float64}
     end