Update lastUpgradeCheck to drop warnings on Xcode versions <= 9.4.1.

PiperOrigin-RevId: 213957515
diff --git a/src/TulsiGenerator/PBXObjects.swift b/src/TulsiGenerator/PBXObjects.swift
index 1c202e9..7da57c7 100644
--- a/src/TulsiGenerator/PBXObjects.swift
+++ b/src/TulsiGenerator/PBXObjects.swift
@@ -1111,7 +1111,7 @@
   }
 
   let compatibilityVersion = XcodeVersionInfo.compatibilityVersion
-  let lastUpgradeCheck = "0940"
+  let lastUpgradeCheck = "0941"
   /// May be set to an Xcode version string indicating the last time a Swift upgrade check was
   /// performed (e.g., 0710).
   var lastSwiftUpdateCheck: String? = nil