Add GHC 8.6.2 build for circle

Author: alanz

.circleci/config.yml

@@ -143,6 +143,10 @@ jobs:
       - STACK_FILE: "stack-8.6.1.yaml"
     <<: *defaults
 
+  ghc-8.6.2:
+    environment:
+      - STACK_FILE: "stack-8.6.2.yaml"
+    <<: *defaults
 
   ghc-nightly:
     environment:
@@ -193,5 +197,6 @@ workflows:
       - ghc-8.4.3
       - ghc-8.4.4
       - ghc-8.6.1
+      - ghc-8.6.2
       - ghc-nightly
       - cabal