Turns on Swift 2.3 flag.

Author: kzaher

RxDataSources.xcodeproj/project.pbxproj

@@ -1076,6 +1076,7 @@
 				OTHER_SWIFT_FLAGS = "-D DEBUG";
 				SDKROOT = iphoneos;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_VERSION = 2.3;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
@@ -1117,6 +1118,7 @@
 				MTL_ENABLE_DEBUG_INFO = NO;
 				OTHER_SWIFT_FLAGS = "";
 				SDKROOT = iphoneos;
+				SWIFT_VERSION = 2.3;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				VALIDATE_PRODUCT = YES;
 				VERSIONING_SYSTEM = "apple-generic";