Downgrade SwiftPM pins format version number

Apparently Github's old ass version of Xcode can't handle a 3 instead
of a 2 here. Whatever.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Cog.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -119,5 +119,5 @@
       }
     }
   ],
-  "version" : 3
+  "version" : 2
 }