Travis update

.travis.yml

@@ -2,6 +2,10 @@
 language: csharp
 solution: ArchiSteamFarm.sln
 
+# Travis lacks universal way of specifying dotnet channel, we need to use absolute one until https://github.com/travis-ci/travis-ci/issues/10059 gets implemented
+# This should be equal to the latest SDK version returned by https://dotnetcli.azureedge.net/dotnet/Sdk/Current/latest.version
+dotnet: 2.1.403
+
 # We can save bandwidth by limiting git clone to only last 10 commits
 git:
   depth: 10
@@ -79,10 +83,9 @@ matrix:
     # We're building ASF with dotnet on latest versions of Linux and OS X
     # Sadly, travis is still missing support for selecting latest images: https://github.com/travis-ci/travis-ci/issues/8922
     - os: linux
-      # Ref: https://docs.travis-ci.com/user/reference/trusty
-      dist: trusty
+      # Ref: https://docs.travis-ci.com/user/reference/xenial
+      dist: xenial
       sudo: false
     - os: osx
       # Ref: https://docs.travis-ci.com/user/reference/osx
-      dotnet: 2.1.403 # For OSX, we need absolute dotnet version until https://github.com/dotnet/core-setup/issues/4187 is resolved
-      osx_image: xcode10
+      osx_image: xcode10.1