build(workflow): update java-version to 21

Author: HappyAreaBean

.github/workflows/dev-jar.yml

@@ -15,7 +15,7 @@ jobs:
         uses: actions/setup-java@v2
         with:
           distribution: 'adopt'
-          java-version: '8'
+          java-version: '21'
       - name: Make gradlew executable
         run: chmod +x ./gradlew
       - name: Build with Gradle