Update actions/checkout: v3 -> v4

Author: yasulab

.github/workflows/scheduler_daily.yml

@@ -24,7 +24,7 @@ jobs:
 
     steps:
     - name: 📥 Download codes from GitHub
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
         fetch-depth: 2
 

.github/workflows/test.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: ☑️ Checkout code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
         fetch-depth: 2
 
@@ -42,7 +42,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: ☑️ Checkout code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
         fetch-depth: 2