Update Project.toml

Author: theogf

test/Project.toml

@@ -24,7 +24,7 @@ Distances = "0.10"
 Documenter = "0.25, 0.26, 0.27"
 FiniteDifferences = "0.10.8, 0.11, 0.12"
 ForwardDiff = "0.10"
-Functors = "0.2"
+Functors = "0.2, 0.3"
 Kronecker = "0.4, 0.5"
 LogExpFunctions = "0.2, 0.3"
 PDMats = "0.9, 0.10, 0.11"