Update checkout action version

Author: Kobzol

.github/workflows/test.yml

@@ -9,7 +9,7 @@ jobs:
     env:
       MDBOOK_VERSION: 0.4.51
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Install mdbook
         run: curl -sSL https://github.com/rust-lang/mdBook/releases/download/v${MDBOOK_VERSION}/mdbook-v${MDBOOK_VERSION}-x86_64-unknown-linux-gnu.tar.gz | tar -xz
       - name: Install mdbook-linkcheck