fix: update deprecated GitHub Actions to v4

- Update actions/checkout from v2 to v4
- Update actions/setup-java from v2 to v4
- Update actions/cache from v2 to v4

These updates fix the CI build failure caused by deprecated
actions/cache@v2 which was automatically failing builds as of
the GitHub Actions deprecation deadline.

All v4 versions are backward compatible with v2.

Co-Authored-By: Sam Fertig <sam.fertig@codeium.com>

Author: devin-ai-integration[bot]

.github/workflows/gradle.yml

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