Update cache action to v4

Author: gurjyan

.github/workflows/build.yaml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@4v
 
     - name: Set up JDK 8
       uses: actions/setup-java@v1