add julia 1.9 to ci

Author: ablaom

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
         version:
           - '1.6'
           - '1' # automatically expands to the latest stable 1.x release of Julia.
-          - 'nightly'
+          - '1.9'
         os:
           - ubuntu-latest
         arch: