Run CI with Java 20 (#122)

Author: slachiewicz

.github/workflows/maven.yml

@@ -25,8 +25,8 @@ jobs:
     name: Build it
     uses: codehaus-plexus/.github/.github/workflows/maven.yml@master
     with:
-      jdk-fast-fail-build: '17'
-      jdk-matrix: '["8", "11", "17"]'
+      jdk-fast-fail-build: '20'
+      jdk-matrix: '["8", "11", "17", "20"]'
       jdk-distribution-matrix: '["temurin"]'
       os-matrix: '["ubuntu-latest","windows-latest", "macOS-latest"]'
       maven_args: 'verify javadoc:javadoc -e -B -V -fae '