drop DomainSets.jl 0.7 from compat

Author: jeremiahpslewis

src/ReinforcementLearningBase/Project.toml

@@ -17,7 +17,7 @@ Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 AbstractTrees = "0.3, 0.4"
 CommonRLInterface = "^0.3.2"
 CommonRLSpaces = "0.2"
-DomainSets = "0.6, 0.7"
+DomainSets = "0.6"
 Reexport = "1"
 julia = "1.3"