Update stack resolver to lts-9.0; Bump syb dep bound

brittany.cabal

@@ -93,7 +93,7 @@ library {
     , mtl >=2.2.1 && <2.3
     , text >=1.2 && <1.3
     , multistate >=0.7.1.1 && <0.8
-    , syb >=0.6 && <0.7
+    , syb >=0.6 && <0.8
     , neat-interpolation >=0.3.2 && <0.4
     , data-tree-print
     , pretty >=1.1.3.3 && <1.2

stack.yaml

@@ -1,8 +1,7 @@
-resolver: lts-8.4
+resolver: lts-9.0
 
 extra-deps:
   - monad-memo-0.4.1
-  - unsafe-0.0
   - czipwith-1.0.0.0
   - butcher-1.1.0.0
   - data-tree-print-0.1.0.0