Update actions/checkout action to v4 (#132)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/run_gradle_task.yml

@@ -56,7 +56,7 @@ jobs:
       ### Gradle task ###
 
       - name: Checkout the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           ref: ${{ inputs.checkout-ref || github.ref }}
 

.github/workflows/run_publish_site.yml

@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           ref: ${{ inputs.checkout-ref || github.ref }}