Update CI workflow: Java 21, actions/checkout@v4, actions/setup-java@v4, actions/cache@v4

Co-Authored-By: david.bean <david.bean@cognition.ai>

Author: devin-ai-integration[bot]

.github/workflows/gradle.yml

@@ -16,13 +16,13 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
-    - name: Set up JDK 11
-      uses: actions/setup-java@v2
+    - uses: actions/checkout@v4
+    - name: Set up JDK 21
+      uses: actions/setup-java@v4
       with:
         distribution: zulu
-        java-version: '11'
-    - uses: actions/cache@v2
+        java-version: '21'
+    - uses: actions/cache@v4
       with:
         path: |
           ~/.gradle/caches