Update Distributions compatibility.

Author: ztangent

Project.toml

@@ -10,7 +10,7 @@ Parameters = "d96e819e-fc66-5662-9728-84c9c7592b0a"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 
 [compat]
-Distributions = "0.21, 0.22, 0.23, 0.24"
+Distributions = "0.21, 0.22, 0.23, 0.24, 0.25"
 Gen = "0.4.3"
 Parameters = "0.12"
 julia = "1.3"