Update default.xml

Add swift-integration-tests to the manifest.

Author: compnerd

default.xml

@@ -31,6 +31,7 @@
   <project remote="github" name="swiftlang/swift-format" path="swift-format" />
   <project remote="github" name="swiftlang/swift-foundation" path="swift-foundation" />
   <project remote="github" name="swiftlang/swift-foundation-icu" path="swift-foundation-icu" />
+  <project remote="github" name="swiftlang/swift-integration-tests" path="swift-integration-tets" groups="notdefault" />
   <project remote="github" name="swiftlang/swift-installer-scripts" path="swift-installer-scripts" />
   <project remote="github" name="swiftlang/swift-llbuild" path="llbuild" />
   <project remote="github" name="swiftlang/swift-lmdb" path="swift-lmdb" />