Fix test-ios by bumping Xcode version (#27356)

Summary:
iOS tests have been failing due to iOS 12.4 not being supported by Xcode 10.2.1. Bumping to 10.3 solves it.

Ideally, we'd bump to Xcode 11.2.1 and iOS 13.2.2. We can do this once all of our internal CI machines have Xcode 11.2.1 available.

## Changelog

[iOS] [Fixed] - Fix CI iOS tests by bumping Xcode version used in Circle CI
Pull Request resolved: https://github.com/facebook/react-native/pull/27356

Test Plan: Circle

Differential Revision: D18765501

Pulled By: hramos

fbshipit-source-id: 1a1ca78c5d8f8596476b0e56740ea1bdf7422161

.circleci/config.yml

@@ -34,7 +34,7 @@ executors:
   reactnativeios:
     <<: *defaults
     macos:
-      xcode: "10.2.1"
+      xcode: "10.3.0"
 
 # -------------------------
 #        COMMANDS
@@ -109,13 +109,13 @@ commands:
     steps:
       - restore_cache:
           keys:
-            - v1-brew
+            - v2-brew
       - steps: << parameters.steps >>
       - save_cache:
           paths:
             - /usr/local/Homebrew
             - ~/Library/Caches/Homebrew
-          key: v1-brew
+          key: v2-brew
 
   with_pods_cache_span:
     parameters:

RNTester/RNTesterIntegrationTests/RNTesterSnapshotTests.m

@@ -38,9 +38,8 @@ RCT_TEST(LayoutExample)
 RCT_TEST(ScrollViewExample)
 RCT_TEST(TextExample)
 #if !TARGET_OS_TV
-// No switch or slider available on tvOS
+// No switch available on tvOS
 RCT_TEST(SwitchExample)
-RCT_TEST(SliderExample)
 #endif
 
 - (void)testZZZNotInRecordMode

scripts/run-ci-e2e-tests.js

@@ -212,12 +212,12 @@ try {
     if (
       tryExecNTimes(
         () => {
-          let destination = 'platform=iOS Simulator,name=iPhone 6s,OS=12.2';
+          let destination = 'platform=iOS Simulator,name=iPhone 6s,OS=12.4';
           let sdk = 'iphonesimulator';
           let scheme = 'HelloWorld';
 
           if (argv.tvos) {
-            destination = 'platform=tvOS Simulator,name=Apple TV,OS=11.4';
+            destination = 'platform=tvOS Simulator,name=Apple TV,OS=12.4';
             sdk = 'appletvsimulator';
             scheme = 'HelloWorld-tvOS';
           }