[libblastrampoline_jll] Fix test

Author: giordano

stdlib/libblastrampoline_jll/test/runtests.jl

@@ -3,5 +3,5 @@
 using Test, Libdl, libblastrampoline_jll
 
 @testset "libblastrampoline_jll" begin
-    @test isa(Libdl.dlsym(Libdl.dlopen(:libblastrampoline), :dgemm_64_), Ptr{Nothing})
+    @test isa(Libdl.dlsym(libblastrampoline_handle, :dgemm_64_), Ptr{Nothing})
 end