Drop all LTS<10 from build

Porges · web-flow · commit 4639cd7318c2 · 2019-09-27T13:46:02.000+12:00
These are causing issues with Stack.
diff --git a/.github/workflows/haskell.yml b/.github/workflows/haskell.yml
@@ -9,11 +9,6 @@ jobs:
       matrix:
         resolver:
         - 'lts'
-        - 'lts-5'
-        - 'lts-6'
-        - 'lts-7'
-        - 'lts-8'
-        - 'lts-9'
         - 'lts-10'
         - 'lts-11'
         - 'lts-12'
