Update actions/checkout to v4

Author: kateinoigakukun

.github/workflows/main.yml

@@ -25,7 +25,7 @@ jobs:
 
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           submodules: recursive
       - id: setup-development
@@ -81,7 +81,7 @@ jobs:
     name: "build-linux (${{ matrix.swift }})"
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Configure container
         run: |
           docker run -dit --name build-container -v $PWD:/workspace -w /workspace swift:${{ matrix.swift }}