use default Xcode instead of pinned since Xcode 12 and Swift 5.3 were released!

Author: 3a4oT

.github/workflows/ci.yaml

@@ -44,8 +44,6 @@ jobs:
         run: make carthage
   swift-package-manager:
     runs-on: macos-latest
-    env:
-      DEVELOPER_DIR: /Applications/Xcode_12.app/Contents/Developer
     steps:
       - name: Checkout
         uses: actions/checkout@v2