Update Travis CI simulator versions and update to the Xcode 11.3 osx_image

Author: tonyarnold

.travis.yml

@@ -1,5 +1,5 @@
 language: swift
-osx_image: xcode10.2
+osx_image: xcode11.3
 
 cache:
   directories:
@@ -14,16 +14,15 @@ jobs:
   include:
       - stage: "Xcode"
         name: "Run tests on iOS"
-        script: xcrun xcodebuild test -destination "platform=iOS Simulator,OS=12.2,name=iPhone X" -workspace "Bond.xcworkspace" -scheme "Bond-iOS"
+        script: xcrun xcodebuild test -destination "platform=iOS Simulator,OS=13.3,name=iPhone 11" -workspace "Bond.xcworkspace" -scheme "Bond-iOS"
         after_success: 'bash <(curl -s https://codecov.io/bash)'
       -
         name: "Build for macOS"
         script: xcrun xcodebuild build -destination "platform=macOS" -workspace "Bond.xcworkspace" -scheme "Bond-macOS"
       -
         name: "Build for tvOS"
-        script: xcrun xcodebuild build -destination "platform=tvOS Simulator,OS=12.2,name=Apple TV 4K" -workspace "Bond.xcworkspace" -scheme "Bond-tvOS"
+        script: xcrun xcodebuild build -destination "platform=tvOS Simulator,OS=13.3,name=Apple TV 4K" -workspace "Bond.xcworkspace" -scheme "Bond-tvOS"
 
       - stage: "Swift Package Manager"
         name: "Run Tests"
-        script: swift test
-        
+        script: swift test --enable-test-discovery