Update actions/cache action to v4 (#56)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/test-java.yml

@@ -17,7 +17,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Cache local Maven repository
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: ~/.m2/repository
           key: build-${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
@@ -38,7 +38,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Cache local Maven repository
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: ~/.m2/repository
           key: javadoc-${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}