CompatHelper: bump compat for "AbstractMCMC" to "0.3" (#169)

Author: github-actions[bot]

Project.toml

@@ -21,7 +21,7 @@ Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 StatsBase = "2913bbd2-ae8a-5f71-8c99-4fb6c76f3a91"
 
 [compat]
-AbstractMCMC = "~0.1, 0.2"
+AbstractMCMC = "~0.1, 0.2, 0.3"
 AxisArrays = "^0.3, 0.4"
 DataFrames = "^0.19, 0.20"
 Distributions = "^0.21, 0.22"