Drop openjdk12 and openjdk13 since these are neither LTS or the latest.
diff --git a/.travis.yml b/.travis.yml
index 91df7bf..a3bd0f4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -20,8 +20,6 @@
     - jdk: oraclejdk11

     - jdk: openjdk8

     - jdk: openjdk11

-    - jdk: openjdk12

-    - jdk: openjdk13

     - jdk: openjdk14

     - jdk: openjdk-ea

   allow_failures: