Update actions/checkout to v4

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Setup Rust
         uses: dtolnay/rust-toolchain@stable
       - name: Configure cache
@@ -26,7 +26,7 @@ jobs:
         toolchain: [stable, "1.68"]
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Setup Rust
         uses: dtolnay/rust-toolchain@master
         with:
@@ -40,7 +40,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Setup Rust (nightly)
         uses: dtolnay/rust-toolchain@nightly
         with:
@@ -66,7 +66,7 @@ jobs:
     continue-on-error: ${{ matrix.checks == 'advisories' }}
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Setup Rust
         uses: dtolnay/rust-toolchain@stable
       - name: Check ${{ matrix.checks }}