Update CI workflow OS selection conditions

Refactor CI workflow to simplify OS selection logic.

Author: epernod

.github/workflows/ci.yml

@@ -19,11 +19,7 @@ on:
         default: false
         type: boolean
 
-env:
-  RUN_MACOS: ${{ !(github.event_name == 'pull_request' ||
-    (github.event_name == 'push' && !startsWith(github.ref, 'refs/tags/v')) ||
-    (github.event_name == 'workflow_dispatch' && inputs.full_build != 'true')) }}
-    
+
 jobs:
   build-and-test:
     name: Run on ${{ matrix.os }} with SOFA ${{ matrix.sofa_branch }} / MeshRefinement=${{ matrix.with_mesh_refinement }}
@@ -47,9 +43,13 @@ jobs:
       fail-fast: false
 
       matrix:
-        os: ${{ fromJSON(env.RUN_MACOS == 'true'
-          && '["ubuntu-22.04","windows-2022","macos-14"]'
-          || '["ubuntu-22.04","windows-2022"]') }}
+        os: ${{ fromJSON(
+          (github.event_name == 'pull_request' ||
+           (github.event_name == 'push' && !startsWith(github.ref, 'refs/tags/v')) ||
+           (github.event_name == 'workflow_dispatch' && inputs.full_build != 'true'))
+          && '["ubuntu-22.04","windows-2022"]'
+          || '["ubuntu-22.04","windows-2022","macos-14"]'
+        ) }}
 
         sofa_branch: [master]
         with_mesh_refinement: [ON, OFF]