Drop Java 8 in CI (#358)

Author: ekrich

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-20.04
     strategy:
       matrix:
-        java: [ '8', '11', '17' ]
+        java: [ '11', '17' ]
     env:
       JAVA_OPTS: -Xms2G -Xmx4G -Xss6M -XX:+UseG1GC -XX:ReservedCodeCacheSize=256M -Dfile.encoding=UTF-8
     name: Test using Java ${{ matrix.java }}