set swift version to 5.0

SwiftyStoreKit.xcodeproj/project.pbxproj

@@ -990,7 +990,7 @@
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = iphoneos;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Debug;
 		};
@@ -1039,7 +1039,7 @@
 				MACOSX_DEPLOYMENT_TARGET = 10.10;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				VALIDATE_PRODUCT = YES;
 			};
 			name = Release;