(chore:flutter) - run sample app on macos

Some xcode project settings were updated due to building for macos

packages/stream_chat_flutter/example/ios/Runner.xcodeproj/project.pbxproj

@@ -3,7 +3,7 @@
 	archiveVersion = 1;
 	classes = {
 	};
-	objectVersion = 46;
+	objectVersion = 50;
 	objects = {
 
 /* Begin PBXBuildFile section */
@@ -156,7 +156,7 @@
 		97C146E61CF9000F007C117D /* Project object */ = {
 			isa = PBXProject;
 			attributes = {
-				LastUpgradeCheck = 1020;
+				LastUpgradeCheck = 1300;
 				ORGANIZATIONNAME = "";
 				TargetAttributes = {
 					97C146ED1CF9000F007C117D = {

packages/stream_chat_flutter/example/ios/Runner.xcodeproj/xcshareddata/xcschemes/Runner.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1020"
+   LastUpgradeVersion = "1300"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"