add GHC 8.8 to testing (#206)

.travis.yml

@@ -21,6 +21,7 @@ env:
     - GHCVER=8.2
     - GHCVER=8.4
     - GHCVER=8.6
+    - GHCVER=8.8
     - GHCVER=nightly
 
 jobs:

stack-8.8.yaml

@@ -0,0 +1,5 @@
+resolver: lts-16.14
+
+packages:
+  - '.'
+  - 'examples'

stack-8.8.yaml.lock

@@ -0,0 +1,12 @@
+# This file was autogenerated by Stack.
+# You should not edit this file by hand.
+# For more information, please see the documentation at:
+#   https://docs.haskellstack.org/en/stable/lock_files
+
+packages: []
+snapshots:
+- completed:
+    size: 532382
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/16/14.yaml
+    sha256: 1ef27e36f38824abafc43224ca612211b3828fa9ffd31ba0fc2867ae2e19ba90
+  original: lts-16.14