Use checkout@v4 instead of deprecated v3 Node.js 16 version

Author: WojciechMazur

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
       matrix:
         scalaversion: ["2.12.19", "2.13.14", "3.3.3"]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: coursier/cache-action@v6
       - uses: coursier/setup-action@v1
         with:
@@ -34,7 +34,7 @@ jobs:
     if: github.event_name == 'push' && startsWith(github.event.ref, 'refs/tags/')
     needs: [build]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: coursier/cache-action@v6
       - uses: coursier/setup-action@v1
         with: