ci: revert changes

Author: DhairyaLGandhi

.github/workflows/Downstream.yml

@@ -61,9 +61,6 @@ jobs:
         with:
           repository: ${{ matrix.package.user }}/${{ matrix.package.repo }}
           path: downstream
-      - name: Checkout SII branch if SciMLSensitivity
-        if: "contains(${{ matrix.package.repo }}, 'SciMLSensitivity.jl')"
-        run: git -C downstream checkout dg/ss
       - name: Load this and run the downstream tests
         shell: julia --color=yes --project=downstream {0}
         run: |