Stop testing on nightly

It's makes the CI status unreliable. We can test upcoming releases in separate PRs.

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
         version:
           - '1' # automatically expands to the latest stable 1.x release of Julia (currently 1.9.x)
           - '~1.10.0-0'
-          - 'nightly'
+          # - 'nightly'
         os:
           - ubuntu-latest
           - macOS-latest