Remove Molly.jl from reverse CI

Molly.jl no longer uses Zygote: JuliaMolSim/Molly.jl#182.

Are there any other packages here which should go? The fewer we have to deal with, the faster CI runs and the fewer false positives we get from it.

Author: ToucheSir

.github/workflows/Downstream.yml

@@ -26,7 +26,6 @@ jobs:
           - {user: SciML, repo: DiffEqFlux.jl, group: Layers}
           - {user: SciML, repo: DiffEqFlux.jl, group: BasicNeuralDE}
           - {user: SciML, repo: NeuralPDE.jl, group: NNPDE}
-          - {user: JuliaMolSim, repo: Molly.jl, group: Zygote}
     steps:
       - uses: actions/checkout@v3
       - uses: julia-actions/setup-julia@v1
@@ -55,4 +54,4 @@ jobs:
             # Mistakenly introducing a breaking change, as we have intentionally made one
             @info "Not compatible with this release. No problem." exception=err
             exit(0)  # Exit immediately, as a success
-          end
+          end