update GitHub Actions to use checkout@v6

Author: JeroenGar

.github/workflows/rust_ci.yml

@@ -22,22 +22,22 @@ jobs:
     name: Run tests (no SIMD)
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
       - run: cargo test --all-targets
 
   tests-simd:
     name: Run tests (SIMD)
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@nightly
       - run: cargo test --all-targets --features=simd
   wasm:
     name: Compile to WASM target
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@nightly
         with:
           targets: wasm32-unknown-unknown

.github/workflows/single_bench.yml

@@ -53,7 +53,7 @@ jobs:
     name: bench ${{ inputs.instance }} (${{ inputs.n_runs }} x ${{ inputs.run_time_s }}s)
     runs-on: ${{ inputs.cpu_tag }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@nightly
       - name: Prepare input JSON
         run: |