Update checkout action

Author: laurynas

.github/workflows/main.yml

@@ -7,7 +7,7 @@ jobs:
       matrix:
         java-version: [ 11, 17, 21, 24 ]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Set up JDK ${{ matrix.java-version }}
         uses: actions/setup-java@v4
         with:
@@ -25,7 +25,7 @@ jobs:
       matrix:
         java-release: [ 21, 24 ]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Set up JDK ${{ matrix.java-release }}
         uses: oracle-actions/setup-java@v1
         with: