Publish 21.

Author: ntwigg

.github/workflows/deploy.yml

@@ -33,10 +33,10 @@ jobs:
       ORG_GRADLE_PROJECT_gpg_key64: ${{ secrets.GPG_KEY64 }}
     steps:
       - uses: actions/checkout@v3
-      - name: jdk 17
+      - name: jdk 21
         uses: actions/setup-java@v3
         with:
-          java-version: 17
+          java-version: 21
           distribution: 'temurin'
       - name: gradle caching
         uses: gradle/actions/setup-gradle@v4