ci(actions): bump checkout action from v3 to v4

Author: marns93

.github/workflows/ci.yml

@@ -9,7 +9,7 @@ jobs:
     timeout-minutes: 5
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Run linter
         run: |
@@ -24,6 +24,6 @@ jobs:
     timeout-minutes: 5
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - run: ./run_tests.sh