Single Pkg.add

Author: gdalle

.github/workflows/Test.yml

@@ -147,8 +147,7 @@ jobs:
           Pkg.Registry.update();
           group = ENV["JULIA_DI_TEST_GROUP"]
           Pkg.activate("./DifferentiationInterface/test/Back/$group");
-          Pkg.develop(; path="./DifferentiationInterface");
-          Pkg.develop(; path="./DifferentiationInterfaceTest");
+          Pkg.add([PackageSpec(; path="./DifferentiationInterface"), PackageSpec(; path="./DifferentiationInterfaceTest")]);
           include("./DifferentiationInterface/test/Back/run_backend.jl");'
       - uses: julia-actions/julia-processcoverage@v1
         with: