Update swift-xcode-playground-support branch to main

Author: shahmishal

utils/update_checkout/update-checkout-config.json

@@ -101,7 +101,7 @@
                 "swift-corelibs-foundation": "main",
                 "swift-corelibs-libdispatch": "main",
                 "swift-integration-tests": "main",
-                "swift-xcode-playground-support": "master",
+                "swift-xcode-playground-support": "main",
                 "ninja": "release",
                 "icu": "release-65-1",
                 "yams": "3.0.1",
@@ -324,7 +324,7 @@
                 "swift-corelibs-foundation": "main",
                 "swift-corelibs-libdispatch": "main",
                 "swift-integration-tests": "main",
-                "swift-xcode-playground-support": "master",
+                "swift-xcode-playground-support": "main",
                 "ninja": "release",
                 "icu": "release-65-1",
                 "yams": "3.0.1",