fix: Adds visionOS deployment to ApolloTestSupport podspec (apollographql/apollo-ios-dev#364)

Author: calvincestari

ApolloTestSupport.podspec

@@ -13,6 +13,7 @@ Pod::Spec.new do |s|
   s.osx.deployment_target = '10.14'
   s.tvos.deployment_target = '12.0'
   s.watchos.deployment_target = '5.0'
+  s.visionos.deployment_target = '1.0'
 
   s.source_files = 'Sources/ApolloTestSupport/*.swift'
   s.dependency 'Apollo', '= ' + version