Only upload artifact on linux

.github/workflows/test-on-pr.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, windows-latest]
+        os: [ubuntu-latest, windows-latest, macos-latest]
 
     steps:
       - name: Checkout code
@@ -40,14 +40,15 @@ jobs:
         run: npm run typecheck --workspace=packages/safe-chain
 
       - name: Create package tarball
+        if: matrix.os == 'ubuntu-latest'
         run: npm pack --workspace=packages/safe-chain
 
       - name: Upload package tarball
         uses: actions/upload-artifact@v4
+        if: matrix.os == 'ubuntu-latest'
         with:
           name: safe-chain-package
           path: aikidosec-safe-chain-*.tgz
-          overwrite: true
 
   e2e-tests:
     name: Run E2E tests