Fix Github workflow

Author: bertfrees

.github/workflows/main.yml

@@ -8,7 +8,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Set up Java
         uses: actions/setup-java@v2
         with:
@@ -20,7 +20,7 @@ jobs:
           gpg-private-key: ${{ secrets.MAVEN_GPG_PRIVATE_KEY }}
           gpg-passphrase: MAVEN_GPG_PASSPHRASE
       - name: Cache downloaded dependencies
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: ~/.m2/repository
           key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}