Upgrade to actions/checkout v5

Author: djc

.github/workflows/ci.yml

@@ -26,7 +26,7 @@ jobs:
         with:
           toolchain: ${{ matrix.rust }}
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v5
       - uses: Swatinem/rust-cache@v2
       - name: Test
         run: cargo test --all-features
@@ -40,7 +40,7 @@ jobs:
         with:
           components: rustfmt, clippy
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v5
       - name: Lint check
         run: cargo lint
       - name: Format check