Github actions: run test on jdk 8, 11 and 13

Author: jknack

.github/workflows/full-build.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        java_version: [1.8, 9, 10, 11, 12, 13]
+        java_version: [1.8, 11, 13]
         os: [ubuntu-latest, windows-latest, macOS-latest]
 
     steps:

.github/workflows/quick-build.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        java_version: [1.8]
+        java_version: [1.8, 11, 13]
         os: [ubuntu-latest]
 
     steps: