Add support for Apple Silicon

-Update classes to read correct Apple Silicon CPU sensor
-Update project to compile a Universal 2 binary. Upgraded Sparkle to 2.1.0 as that was the latest and supports ARM64.
-Add MacBookPro18,1 to Machines.plist

Sparkle.framework/Versions/B/Headers/SPUUpdateCheck.h

@@ -0,0 +1,33 @@
+//
+//  SPUUpdateCheck.h
+//  SPUUpdateCheck
+//
+//  Created by Mayur Pawashe on 8/28/21.
+//  Copyright © 2021 Sparkle Project. All rights reserved.
+//
+
+#ifndef SPUUpdateCheck_h
+#define SPUUpdateCheck_h
+
+/**
+ Describes the type of update check being performed.
+ 
+ Each update check corresponds to an update check method on `SPUUpdater`.
+ */
+typedef NS_ENUM(NSInteger, SPUUpdateCheck)
+{
+    /**
+     The user-initiated update check corresponding to `-[SPUUpdater checkForUpdates]`.
+     */
+    SPUUpdateCheckUpdates = 0,
+    /**
+     The background scheduled update check corresponding to `-[SPUUpdater checkForUpdatesInBackground]`.
+     */
+    SPUUpdateCheckUpdatesInBackground = 1,
+    /**
+     The informational probe update check corresponding to `-[SPUUpdater checkForUpdateInformation]`.
+     */
+    SPUUpdateCheckUpdateInformation = 2
+};
+
+#endif /* SPUUpdateCheck_h */