Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/rust.yml

@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6
       - uses: dtolnay/rust-toolchain@v1
         with:
           toolchain: stable
@@ -37,7 +37,7 @@ jobs:
     name: Test Suite
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6
       - uses: dtolnay/rust-toolchain@v1
         with:
           # update `cargo-expand` accordingly, when bumping MSRV:
@@ -51,7 +51,7 @@ jobs:
     name: Rustfmt
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6
       - uses: dtolnay/rust-toolchain@v1
         with:
           toolchain: stable
@@ -62,7 +62,7 @@ jobs:
     name: Clippy
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6
       - uses: dtolnay/rust-toolchain@v1
         with:
           toolchain: stable
@@ -73,7 +73,7 @@ jobs:
     name: Compile and test with minimal versions
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6
       - uses: dtolnay/rust-toolchain@v1
         with:
           toolchain: nightly
@@ -91,7 +91,7 @@ jobs:
     name: Verify minimal supported rust version
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6
       - uses: dtolnay/rust-toolchain@v1
         with:
           toolchain: nightly