Update actions/cache action to v6

Author: renovate[bot]

.github/workflows/codecov.yml

@@ -17,7 +17,7 @@ jobs:
         with:
           distribution: 'temurin'
           java-version: 21
-      - uses: actions/cache@v5
+      - uses: actions/cache@v6
         with:
           path: ~/.m2/repository
           key: maven-${{ hashFiles('**/pom.xml') }}

.github/workflows/mvn.yml

@@ -24,7 +24,7 @@ jobs:
         with:
           distribution: 'temurin'
           java-version: ${{ matrix.java }}
-      - uses: actions/cache@v5
+      - uses: actions/cache@v6
         with:
           path: ~/.m2/repository
           key: ${{ runner.os }}-jdk-${{ matrix.java }}-maven-${{ hashFiles('**/pom.xml') }}