Fix release build issue

Author: wkh237

src/ios/RNFetchBlob.xcodeproj/project.pbxproj

@@ -198,7 +198,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 7.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
 				MTL_ENABLE_DEBUG_INFO = YES;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = iphoneos;
@@ -236,7 +236,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 7.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				VALIDATE_PRODUCT = YES;