CI: reenable Ubuntu native build

.github/workflows/CI_master.yml

@@ -52,12 +52,12 @@ jobs:
     with:
       artifactBasename: Pixi-${{ github.run_id }}
 
-#  Ubuntu:
-#    needs: [Prepare]
-#    if: "!startsWith(github.head_ref, 'refs/heads/backport-')"
-#    uses: ./.github/workflows/sub_buildUbuntu.yml
-#    with:
-#      artifactBasename: Ubuntu-${{ github.run_id }}
+  Ubuntu:
+    needs: [Prepare]
+    if: "!startsWith(github.head_ref, 'refs/heads/backport-')"
+    uses: ./.github/workflows/sub_buildUbuntu.yml
+    with:
+      artifactBasename: Ubuntu-${{ github.run_id }}
 
   Windows:
     needs: [Prepare]
@@ -83,6 +83,7 @@ jobs:
     needs: [
         Prepare,
         Pixi,
+        Ubuntu,
         Windows,
         Lint
       ]