CompatHelper: bump compat for Functors to 0.4, (keep existing compat) (#121)

Co-authored-by: CompatHelper Julia <compathelper_noreply@julialang.org>

Author: github-actions[bot]

Project.toml

@@ -12,7 +12,7 @@ Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 
 [compat]
 ChainRulesCore = "1"
-Functors = "0.3"
+Functors = "0.3, 0.4"
 Zygote = "0.6.40"
 julia = "1.6"