.travis.yml in async-io-1.18.2 vs .travis.yml in async-io-1.18.3

@@ -6,9 +6,11 @@
   include:
     - rvm: 2.3
     - rvm: 2.4
     - rvm: 2.5
     - rvm: 2.6
+    - rvm: 2.6
+      env: COVERAGE=PartialSummary,Coveralls
     - rvm: truffleruby
     - rvm: jruby-head
       env: JRUBY_OPTS="--debug -X+O"
     - rvm: ruby-head
   allow_failures: