Update swift-corelibs-libdispatch branch to main

Author: shahmishal

utils/update_checkout/update-checkout-config.json

@@ -69,7 +69,7 @@
                 "swift-stress-tester": "main",
                 "swift-corelibs-xctest": "main",
                 "swift-corelibs-foundation": "main",
-                "swift-corelibs-libdispatch": "master",
+                "swift-corelibs-libdispatch": "main",
                 "swift-integration-tests": "master",
                 "swift-xcode-playground-support": "master",
                 "ninja": "release",
@@ -99,7 +99,7 @@
                 "swift-stress-tester": "main",
                 "swift-corelibs-xctest": "main",
                 "swift-corelibs-foundation": "main",
-                "swift-corelibs-libdispatch": "master",
+                "swift-corelibs-libdispatch": "main",
                 "swift-integration-tests": "master",
                 "swift-xcode-playground-support": "master",
                 "ninja": "release",
@@ -322,7 +322,7 @@
                 "swift-stress-tester": "main",
                 "swift-corelibs-xctest": "main",
                 "swift-corelibs-foundation": "main",
-                "swift-corelibs-libdispatch": "master",
+                "swift-corelibs-libdispatch": "main",
                 "swift-integration-tests": "master",
                 "swift-xcode-playground-support": "master",
                 "ninja": "release",