fix: change deployment target

Author: MichaelVerdon

tests/macos/Podfile

@@ -41,5 +41,11 @@ end
 post_install do |installer|
   installer.pods_project.targets.each do |target|
     flutter_additional_macos_build_settings(target)
+    
+    target.build_configurations.each do |config|
+      if config.build_settings['MACOSX_DEPLOYMENT_TARGET'].to_f < 10.13
+        config.build_settings['MACOSX_DEPLOYMENT_TARGET'] = '10.13'
+      end
+    end
   end
 end