ci: update to actions/checkout v4 (#1131)

Author: tottoto

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install rust
         uses: dtolnay/rust-toolchain@stable
@@ -61,7 +61,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install rust
         uses: dtolnay/rust-toolchain@master
@@ -81,7 +81,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install Rust
         uses: dtolnay/rust-toolchain@nightly