Bump resolvers to lts-8.20

.travis.yml

 # Test against different stack LTS versions.
 env:
- - DISPLAY=true   RESOLVER=lts-8.19 # GHC 8.0.2
+ - DISPLAY=true   RESOLVER=lts-8.20 # GHC 8.0.2
 
 # Choose a lightweight base image; we provide our own build tools.
 language: python

ihaskell-display/ihaskell-aeson/stack.yaml

 flags: {}
 packages:
 - '.'
-resolver: lts-8.19
+resolver: lts-8.20

ihaskell-display/ihaskell-blaze/stack.yaml

 flags: {}
 packages:
 - '.'
-resolver: lts-8.19
+resolver: lts-8.20

ihaskell-display/ihaskell-charts/stack.yaml

 flags: {}
 packages:
 - '.'
-resolver: lts-8.19
+resolver: lts-8.20

ihaskell-display/ihaskell-diagrams/stack.yaml

 flags: {}
 packages:
 - '.'
-resolver: lts-8.19
+resolver: lts-8.20

ihaskell-display/ihaskell-gnuplot/stack.yaml

 flags: {}
 packages:
 - '.'
-resolver: lts-8.19
+resolver: lts-8.20
 extra-deps: []

ihaskell-display/ihaskell-hatex/stack.yaml

 flags: {}
 packages:
 - '.'
-resolver: lts-8.19
+resolver: lts-8.20

ihaskell-display/ihaskell-juicypixels/stack.yaml

 flags: {}
 packages:
 - '.'
-resolver: lts-8.19
+resolver: lts-8.20

ihaskell-display/ihaskell-magic/stack.yaml

 flags: {}
 packages:
 - '.'
-resolver: lts-8.19
+resolver: lts-8.20

ihaskell-display/ihaskell-plot/stack.yaml

 flags: {}
 packages:
 - '.'
-resolver: lts-8.19
+resolver: lts-8.20

ihaskell-display/ihaskell-rlangqq/stack.yaml

 flags: {}
 packages:
 - '.'
-resolver: lts-8.19
+resolver: lts-8.20

ihaskell-display/ihaskell-static-canvas/stack.yaml

 flags: {}
 packages:
 - '.'
-resolver: lts-8.19
+resolver: lts-8.20

ihaskell-display/ihaskell-widgets/stack.yaml

 flags: {}
 packages:
 - '.'
-resolver: lts-8.19
+resolver: lts-8.20

stack.yaml

@@ -14,7 +14,7 @@ packages:
     - ./ihaskell-display/ihaskell-plot
     - ./ihaskell-display/ihaskell-static-canvas
     - ./ihaskell-display/ihaskell-widgets
-resolver: lts-8.19
+resolver: lts-8.20
 extra-deps: []
 flags:
   ihaskell: