.travis.yml in async-io-1.24.0 vs .travis.yml in async-io-1.25.0

@@ -12,9 +12,14 @@
       env: COVERAGE=PartialSummary,Coveralls
     - rvm: truffleruby
     - rvm: jruby-head
       env: JRUBY_OPTS="--debug -X+O"
     - rvm: ruby-head
+    - rvm: 2.6
+      os: osx
+    - rvm: 2.6
+      os: osx
+      gemfile: gems/nio4r-2.3.gemfile
   allow_failures:
     - rvm: ruby-head
     - rvm: truffleruby
     - rvm: jruby-head