Merge pull request #11 from sullis/ci-jdk-8-11-15

ci: JDK 8, JDK 11, JDK 15
diff --git a/.github/workflows/maven.yml b/.github/workflows/maven.yml
index 3b0c099..a519c12 100644
--- a/.github/workflows/maven.yml
+++ b/.github/workflows/maven.yml
@@ -23,7 +23,7 @@
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [ '1.8', '11.0.4', '12.0.2' ]
+        java: [ '8', '11', '15' ]
         
     steps:
     - uses: actions/checkout@v2