bump Observables compat

Author: baumgold

Project.toml

@@ -14,7 +14,7 @@ WebIO = "0f1e0344-ec1d-5b48-a673-e5cf874b6c29"
 [compat]
 JSExpr = "0.4, 0.5"
 JSON = "0.18, 0.19, 0.20, 0.21"
-Observables = "0.2, 0.3, 0.4"
+Observables = "0.2, 0.3, 0.4, 0.5"
 Tables = "1"
 WebIO = "0.8"
 julia = "0.7, 1"