chore: update XCode version

scope_guard.xcodeproj/xcshareddata/xcschemes/scope_guard.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1340"
+   LastUpgradeVersion = "1640"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"