Specify osx image separately for each config

Author: jakubvano

.travis.yml

@@ -1,5 +1,4 @@
 language: objective-c
-osx_image: xcode10.2
 env:
   global:
     - LC_CTYPE=en_US.UTF-8
@@ -20,18 +19,34 @@ matrix:
         - swift build
         - swift test
     - env: JOB="POD_LINT"
+      osx_image: xcode10
       script:
         - bundle exec pod lib lint
     - env: JOB="XCODE" DEST="OS=9.3,name=iPhone 6" SCHEME="Swinject-iOS" SDK="iphonesimulator" ACTION="test"
+      osx_image: xcode10
     - env: JOB="XCODE" DEST="OS=10.3.1,name=iPhone 7 Plus" SCHEME="Swinject-iOS" SDK="iphonesimulator" ACTION="test"
+      osx_image: xcode10
     - env: JOB="XCODE" DEST="OS=11.2,name=iPhone 8 Plus" SCHEME="Swinject-iOS" SDK="iphonesimulator" ACTION="test"
+      osx_image: xcode10
+    - env: JOB="XCODE" DEST="OS=12.2,name=iPhone X" SCHEME="Swinject-iOS" SDK="iphonesimulator" ACTION="test"
+      osx_image: xcode10.2
     - env: JOB="XCODE" DEST="arch=x86_64" SCHEME="Swinject-OSX" SDK="macosx" ACTION="test"
+      osx_image: xcode10
+    - env: JOB="XCODE" DEST="arch=x86_64" SCHEME="Swinject-OSX" SDK="macosx" ACTION="test"
+      osx_image: xcode10.2
     - env: JOB="XCODE" DEST="OS=9.2,name=Apple TV 1080p" SCHEME="Swinject-tvOS" SDK="appletvsimulator" ACTION="test"
+      osx_image: xcode10
     - env: JOB="XCODE" DEST="OS=10.2,name=Apple TV 1080p" SCHEME="Swinject-tvOS" SDK="appletvsimulator" ACTION="test"
+      osx_image: xcode10
     - env: JOB="XCODE" DEST="OS=11.0,name=Apple TV 4K" SCHEME="Swinject-tvOS" SDK="appletvsimulator" ACTION="test"
+      osx_image: xcode10
     - env: JOB="XCODE" DEST="OS=2.2,name=Apple Watch - 42mm" SCHEME="Swinject-watchOS" SDK="watchsimulator" ACTION="build"
+      osx_image: xcode10
     - env: JOB="XCODE" DEST="OS=3.2,name=Apple Watch - 42mm" SCHEME="Swinject-watchOS" SDK="watchsimulator" ACTION="build"
+      osx_image: xcode10
     - env: JOB="XCODE" DEST="OS=4.0,name=Apple Watch - 42mm" SCHEME="Swinject-watchOS" SDK="watchsimulator" ACTION="build"
+      osx_image: xcode10
+
 before_install:
   - curl -L -O https://github.com/Carthage/Carthage/releases/download/0.28.0/Carthage.pkg
   - sudo installer -pkg Carthage.pkg -target /