update xcode version in github actions

Author: OhKanghoon

.github/workflows/ci.yml

@@ -12,20 +12,20 @@ jobs:
     strategy:
       matrix:
         env:
-          - sdk: iphonesimulator13.0
-            destination: platform=iOS Simulator,name=iPhone 11 Pro,OS=13.0
+          - sdk: iphonesimulator
+            destination: platform=iOS Simulator,name=iPhone 12 Pro,OS=latest
 
-          - sdk: macosx10.15
+          - sdk: macosx
             destination: arch=x86_64
 
-          - sdk: appletvsimulator13.0
-            destination: OS=13.0,name=Apple TV
+          - sdk: appletvsimulator
+            destination: platform=tvOS Simulator,name=Apple TV,OS=latest
 
     steps:
     - uses: actions/checkout@v1
 
-    - name: Select Xcode
-      run: sudo xcode-select -s /Applications/Xcode_11.app
+    - name: Select Xcode 12.4
+      run: sudo xcode-select -s /Applications/Xcode_12.4.app
 
     - name: Generate Xcode Project
       run: swift package generate-xcodeproj --enable-code-coverage