Update the llvm-project branch per the rebranch. (#840)

Author: hjyamauchi

default.xml

@@ -6,7 +6,7 @@
 
   <manifest-server url="http://stable.swift.dt.compnerd.org"/>
 
-  <project remote="github" name="swiftlang/llvm-project" path="llvm-project" revision="stable/20230725" />
+  <project remote="github" name="swiftlang/llvm-project" path="llvm-project" revision="stable/20240723" />
   <project remote="github" name="swiftlang/indexstore-db" path="indexstore-db" />
   <project remote="github" name="swiftlang/sourcekit-lsp" path="sourcekit-lsp" />
   <project remote="github" name="swiftlang/swift" path="swift" />