Drop Oracle JDK 8 since it is not supported anymore.

Gary Gregory · Gary Gregory · commit f740643e53e7 · 2019-08-14T11:37:52.000-07:00
diff --git a/.travis.yml b/.travis.yml
@@ -16,11 +16,11 @@
 language: java
 
 jdk:
-  - oraclejdk8
   - oraclejdk11
   - openjdk8
   - openjdk11
   - openjdk12
+  - openjdk13
   - openjdk-ea
 
 after_success:
