Merge pull request #69 from SethTisue/scala-2.13.4

Scala 2.13.4 (was 2.13.3)

Author: SethTisue

.travis.yml

@@ -5,7 +5,7 @@ import: scala/scala-dev:travis/default.yml
 language: scala
 
 scala:
-  - 2.13.3
+  - 2.13.4
 
 env:
   - SCALAJS_BUILD=     ADOPTOPENJDK=8