Add downstream tests for Lux.jl

Author: avik-pal

.github/workflows/Downstream.yml

@@ -22,6 +22,7 @@ jobs:
           - {user: denizyuret, repo: Knet.jl, group: All}
           - {user: dfdx, repo: Avalon.jl, group: All}
           - {user: JuliaOptimalTransport, repo: OptimalTransport.jl, group: All}
+          - {user: avik-pal, repo: Lux.jl, group: All}
     steps:
       - uses: actions/checkout@v3
       # for OptimalTransport.jl