Remove finite differences

Author: CarloLucibello

Project.toml

@@ -8,7 +8,6 @@ Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"
 CUDA = "052768ef-5323-5732-b1bb-66c8b64840ba"
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
-FiniteDifferences = "26cc04aa-876d-5657-8c51-4c34ba976000"
 Flux = "587475ba-b771-5e3f-ad9e-33799f191a9c"
 Functors = "d9f16b24-f501-4c13-a1f2-28368ffc5196"
 Graphs = "86223c79-3864-5bf0-83f7-82e725a168b6"