build: use v4 of various GH actions

.github/workflows/build.yml

@@ -13,21 +13,21 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Set up JDK 17
-        uses: actions/setup-java@v2
+        uses: actions/setup-java@v4
         with:
           java-version: '17'
           distribution: 'adopt'
       - name: Cache Maven packages
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: ~/.m2/repository
           key: ${{ runner.os }}-m2-${{ hashFiles('.github/workflows/**/*.*', '**/pom.xml', '**/META-INF/MANIFEST.MF', 'build/de.cau.cs.kieler.spviz.targetplatform/de.cau.cs.kieler.spviz.targetplatform.target') }}
       - name: Build with Maven
         run: mvn --batch-mode --update-snapshots -f build/pom.xml verify
       - name: Archive P2 Repository
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: SPViz P2 Repository
           path: build/de.cau.cs.kieler.spviz.repository/target/repository/**/*