update CI to run on 1.10 (LTS) instead of 1.6, which is no longer supported

Author: ajwheeler

.github/workflows/CI.yml

@@ -13,7 +13,7 @@ jobs:
       fail-fast: false
       matrix:
         version:
-          - '1.6'
+          - '1.10'
           - '1'
           - 'nightly'
         os: