[GitHub Actions] Rename macOS job to Xcode job in swiftpm.yml

.github/workflows/swiftpm.yml

@@ -18,7 +18,7 @@ on:
       - 'Tests/*/*'
 
 jobs:
-  macOS:
+  Xcode:
     strategy:
       matrix:
         xcode: ['10','10.1','10.2','10.2.1','10.3','11']