Update .travis.yml

Author: paulofaria

.travis.yml

@@ -18,7 +18,7 @@ matrix:
 script:
   - swift build -c release
   - swift build
-  - swift test
+  - swift test --enable-test-discovery
   - 'if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
        eval "$(curl -sL https://raw.githubusercontent.com/lgaches/swifttravisci/master/codecov)";
      fi'