[Makefile] Point to xcode12.1 xip file. (#9974)

Co-authored-by: Manuel de la Pena <mandel@microsoft.com>

Make.config

@@ -112,7 +112,7 @@ WATCHOS_NUGET_VERSION_FULL=$(WATCHOS_NUGET_VERSION_NO_METADATA)+$(NUGET_BUILD_ME
 
 # Xcode version should have both a major and a minor version (even if the minor version is 0)
 XCODE_VERSION=12.1
-XCODE_URL=http://xamarin-storage/bot-provisioning/xcodes/Xcode_12.1_GM_seed.xip
+XCODE_URL=http://xamarin-storage/bot-provisioning/xcodes/Xcode_12.1.xip
 XCODE_DEVELOPER_ROOT=/Applications/Xcode_12.1.0-GM.app/Contents/Developer
 XCODE_PRODUCT_BUILD_VERSION:=$(shell /usr/libexec/PlistBuddy -c 'Print :ProductBuildVersion' $(XCODE_DEVELOPER_ROOT)/../version.plist)