fix: update ci to use jdk21

.github/workflows/build.yml

@@ -22,7 +22,7 @@ jobs:
         java-version: 21
         java-package: jdk
 
-    - uses: actions/cache@v2
+    - uses: actions/cache@v4
       with:
         path: |
           ~/.gradle/caches
@@ -46,7 +46,7 @@ jobs:
       continue-on-error: true
 
     - name: Upload Artifact
-      uses: actions/upload-artifact@v2
+      uses: actions/upload-artifact@v4
       with:
         name: c2me-artifact
         path: 'build/libs/*.jar'

.github/workflows/test.yml

@@ -14,19 +14,19 @@ jobs:
         testTask: [runTestC2MEServer]
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
       with:
         fetch-depth: 0
         submodules: true
 
-    - name: Set up JDK 17
+    - name: Set up JDK 21
       uses: actions/setup-java@v2
       with:
         distribution: 'zulu'
-        java-version: 17
+        java-version: 21
         java-package: jdk
 
-    - uses: actions/cache@v2
+    - uses: actions/cache@v4
       with:
         path: |
           ~/.gradle/caches

Jenkinsfile

@@ -9,7 +9,7 @@ pipeline {
         }
         stage('Build') {
             tools {
-                jdk "OpenJDK 17"
+                jdk "OpenJDK 21"
             }
             steps {
                 withMaven(