[ci] Drop jdk12 as no longer supported

hazendaz · hazendaz · commit 6fb6eb1781fb · 2020-01-19T17:34:05.000-05:00
diff --git a/.travis.yml b/.travis.yml
@@ -3,7 +3,6 @@ language: java
 jdk:
   - openjdk-ea
   - openjdk13
-  - openjdk12
   - openjdk11
   - openjdk8
 
