bump SliceSampling compat for docs

Author: Red-Portal

docs/Project.toml

@@ -25,7 +25,7 @@ PDMats = "0.11"
 Plots = "1"
 PrettyTables = "2"
 Random = "1"
-SliceSampling = "0.6, 0.7"
+SliceSampling = "0.8"
 StableRNGs = "1"
 Statistics = "1"
 Turing = "0.34, 0.35"