Update to checkout v6

Author: nicholasbishop

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
     name: cargo +nightly build
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install latest nightly
         uses: dtolnay/rust-toolchain@nightly

.github/workflows/release.yml

@@ -15,7 +15,7 @@ jobs:
   release:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: rust-lang/crates-io-auth-action@v1
         id: auth
       - run: cargo install auto-release