update travis to build ios 12.1, 11.4, 9.1, and tvos 12.1

Author: thomaszurkan-optimizely

.travis.yml

@@ -59,13 +59,13 @@ jobs:
         - slather
         - sleep 5 # https://github.com/travis-ci/travis-ci/issues/4725
     - <<: *unittests
-      env: SCHEME=OptimizelySwiftSDK-iOS TEST_SDK=iphonesimulator PLATFORM='iOS Simulator' OS=10.1 NAME='iPhone 7 Plus'
-      name: PLATFORM='iOS Simulator' OS=10.1 NAME='iPhone 7 Plus'
+      env: SCHEME=OptimizelySwiftSDK-iOS TEST_SDK=iphonesimulator PLATFORM='iOS Simulator' OS=11.4 NAME='iPhone 7 Plus'
+      name: PLATFORM='iOS Simulator' OS=11.4 NAME='iPhone 7 Plus'
     - <<: *unittests
-      env: SCHEME=OptimizelySwiftSDK-iOS TEST_SDK=iphonesimulator PLATFORM='iOS Simulator' OS=10.3.1 NAME='iPhone 7'
-      name: PLATFORM='iOS Simulator' OS=10.3.1 NAME='iPhone 7'
+      env: SCHEME=OptimizelySwiftSDK-iOS TEST_SDK=iphonesimulator PLATFORM='iOS Simulator' OS=12.1 NAME='iPhone 7'
+      name: PLATFORM='iOS Simulator' OS=12.1 NAME='iPhone 7'
     - <<: *unittests
-      env: SCHEME=OptimizelySwiftSDK-tvOS TEST_SDK=appletvsimulator PLATFORM='tvOS Simulator' OS=10.2 NAME='Apple TV 1080p'
+      env: SCHEME=OptimizelySwiftSDK-tvOS TEST_SDK=appletvsimulator PLATFORM='tvOS Simulator' OS=12.1 NAME='Apple TV 1080p'
       name: PLATFORM='tvOS Simulator' OS=10.2 NAME='Apple TV 1080p'
 
     - stage: 'Prepare for release'