Merge pull request #984 from c-bata/update-actions-checkout

Update `actions/checkout` to v4

.github/workflows/docker-ghcr.yml

@@ -7,7 +7,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - run: echo "REPO=${GITHUB_REPOSITORY,,}" >> $GITHUB_ENV
       - run: echo "TAG=${GITHUB_REF##*/}" >> $GITHUB_ENV
       - name: Enable buildx

.github/workflows/e2e-dashboard-tests.yml

@@ -22,7 +22,7 @@ jobs:
       matrix:
         optuna-version: ['optuna==3.1.0', 'git+https://github.com/optuna/optuna.git']
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: Setup Node
         uses: actions/setup-node@v2

.github/workflows/e2e-standalone-tests.yml

@@ -22,7 +22,7 @@ jobs:
       matrix:
         optuna-version: ['optuna']
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Install Rust toolchains
         uses: dtolnay/rust-toolchain@stable

.github/workflows/gh-pages.yml

@@ -25,7 +25,7 @@ jobs:
     if: github.repository == 'optuna/optuna-dashboard'
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Install Rust toolchains
         uses: dtolnay/rust-toolchain@stable
       - name: Install wasm-pack

.github/workflows/github-release.yml

@@ -10,7 +10,7 @@ jobs:
     name: Build and publish Python distributions to TestPyPI and PyPI
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: Setup Node
         uses: actions/setup-node@v2

.github/workflows/pypi-publish.yml

@@ -12,7 +12,7 @@ jobs:
     permissions:
       id-token: write
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Setup Node
       uses: actions/setup-node@v2
       with:

.github/workflows/python-coverage.yml

@@ -15,7 +15,7 @@ jobs:
 
     steps:
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Setup Python
       uses: actions/setup-python@v4

.github/workflows/python-tests.yml

@@ -11,7 +11,7 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Set up Python
         uses: actions/setup-python@v4
         with: