Updated PlaygroundSupport and XCPlayground to Swift 5.

Author: cwakamo

PlaygroundSupport/PlaygroundSupport.xcodeproj/project.pbxproj

@@ -1295,7 +1295,7 @@
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
 				SWIFT_STDLIB = swiftCore;
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Debug;
 		};
@@ -1333,7 +1333,7 @@
 				GCC_WARN_UNUSED_VARIABLE = YES;
 				SWIFT_SKIP_IMPLICIT_STDLIB_RUNPATH_SEARCH_PATH = YES;
 				SWIFT_STDLIB = swiftCore;
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Release;
 		};