Merge pull request #2 from rasheedja/junaidr/upgrade-stackage-lts

Upgrade to latest stackage lts

Author: rasheedja

stack.yaml

@@ -18,7 +18,7 @@
 # resolver: ./custom-snapshot.yaml
 # resolver: https://example.com/snapshots/2018-01-01.yaml
 resolver:
-  url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/19/15.yaml
+  url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/20/17.yaml
 
 # User packages to be built.
 # Various formats can be used as shown in the example below.