Update pr-validation-test.yml

Author: dmercuriali

.github/workflows/pr-validation-test.yml

@@ -31,7 +31,7 @@ jobs:
         with:
           java-version: '11'
       - name: 'Cache Maven packages'
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: ~/.m2
           key: 'cache'