Issue #204 -- update java to 21 and other updates -- update setup version

Author: tballison

.github/workflows/main-jdk21-build.yml

@@ -30,7 +30,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Set up JDK 21
-        uses: actions/setup-java@v2
+        uses: actions/setup-java@v4
         with:
           java-version: 21
           distribution: 'zulu'#may need to move to liberica