test against Foreman 3.12, not develop

Author: evgeni

.github/workflows/ruby_tests.yml

@@ -24,7 +24,7 @@ jobs:
       fail-fast: false
       matrix:
         foreman:
-          - develop
+          - '3.12'
     uses: theforeman/actions/.github/workflows/foreman_plugin.yml@v0
     with:
       plugin: foreman_rh_cloud