Removing VALID_ARCHS from iOS podspec (#505)

ios/fluttertoast.podspec

@@ -16,6 +16,6 @@ Toast Library for FLutter
   s.public_header_files = 'Classes/**/*.h'
   s.dependency 'Flutter'
   s.dependency 'Toast'
-  s.pod_target_xcconfig = {'VALID_ARCHS' => 'x86_64 armv7 arm64', 'DEFINES_MODULE' => 'YES'}
+  s.pod_target_xcconfig = {'DEFINES_MODULE' => 'YES'}
   s.resource_bundles = {'fluttertoast_privacy' => ['Resources/PrivacyInfo.xcprivacy']}
 end