Remove unneeded dependencies from the package

Project.toml

@@ -5,12 +5,9 @@ version = "0.5.4"
 
 [deps]
 Libdl = "8f399da3-3557-5675-b5ff-fb832c97cbdb"
-Pkg = "44cfe95a-1eb2-52ea-b672-e2afdf69b78f"
 SBML_jll = "bb12108a-f4ef-5f88-8ef3-0b33ff7017f1"
-SHA = "ea8e919c-243c-51af-8825-aaa63cd721ce"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 Symbolics = "0c5d862f-8b57-4792-8d23-62f2024744c7"
-Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
 julia = "1.5"
@@ -18,6 +15,8 @@ Symbolics = "0.1.21, 1"
 
 [extras]
 Downloads = "f43a241f-c20a-4ad4-852c-f6b1247861c6"
+SHA = "ea8e919c-243c-51af-8825-aaa63cd721ce"
+Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["Downloads"]
+test = ["Downloads", "SHA", "Test"]

src/SBML.jl

 module SBML
 
-using SBML_jll, Libdl, Pkg
+using SBML_jll, Libdl
 using SparseArrays
 using Symbolics
 

test/runtests.jl

@@ -3,7 +3,6 @@ using Test, SHA, SparseArrays, Downloads
 using SBML
 using SBML: Model, Reaction, Species
 using Symbolics
-import Pkg
 
 @testset "SBML test suite" begin
     include("version.jl")

test/version.jl

 
 @testset "CCall to SBML works and SBML returns a version" begin
-    @test typeof(SBMLVersion()) == Pkg.VersionNumber
+    @test SBMLVersion() isa VersionNumber
 end