Use setup-swift v2 for Linux (v3 GPG issue)

Author: ivan-magda

.github/workflows/ci.yml

@@ -57,7 +57,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Set up Swift
-        uses: swift-actions/setup-swift@v3
+        uses: swift-actions/setup-swift@v2
         with:
           swift-version: "6.2"