update actions/checkout to v4

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
       fail-fast: true
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
       - uses: Swatinem/rust-cache@v2
       - run: cargo test --features=search
@@ -21,7 +21,7 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
         with:
           components: clippy,rustfmt