Update actions/checkout action to v4

.github/workflows/docker.yml

@@ -10,7 +10,7 @@ jobs:
     name: Docker build and push
     runs-on: ubuntu-22.04
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
       with:
         submodules: 'recursive'
     - name: Login to DockerHub

.github/workflows/test.yml

@@ -15,7 +15,7 @@ jobs:
       matrix:
         jdk: [11, 13, 19]
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
       with:
         submodules: 'recursive'
     - name: Set up JDK
@@ -29,7 +29,7 @@ jobs:
     name: Assembly test
     runs-on: ubuntu-22.04
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
       with:
         submodules: 'recursive'
     - name: Set up JDK