Restore docs MarginalLogDensities compat

Author: yebai

docs/Project.toml

@@ -37,7 +37,7 @@ FillArrays = "0.13, 1"
 ForwardDiff = "0.10, 1"
 LogDensityProblems = "2"
 MCMCChains = "5, 6, 7"
-MarginalLogDensities = "0.4.3"
+MarginalLogDensities = "0.4"
 OrderedCollections = "1"
 StableRNGs = "1"
 StatsFuns = "1"