run CI on julia 1.8 (#707)

* run CI on julia 1.8

* Disable CI on '1' (redundant)

Author: simonbyrne

.github/workflows/test.yml

@@ -20,8 +20,8 @@ jobs:
       matrix:
         julia-version:
           - '1.6'
-          - '1'
           - '1.7'
+          - '~1.8.0-0'
           - 'nightly'
         julia-arch:
           - 'x64'