Update runtests.jl

Author: ChrisRackauckas

test/runtests.jl

@@ -11,7 +11,7 @@ function activate_gpu_env()
     Pkg.instantiate()
 end
 
-if GROUP == "All"
+if GROUP == "Core" || GROUP == "All"
     @time @safetestset "Exact coloring via contraction" begin include("test_contraction.jl") end
     @time @safetestset "Greedy distance-1 coloring" begin include("test_greedy_d1.jl") end
     @time @safetestset "Greedy star coloring" begin include("test_greedy_star.jl") end