chore(deps): update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/cd.yaml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
           token: ${{ secrets.RELEASE_PLZ_TOKEN }}

.github/workflows/ci.yml

@@ -38,7 +38,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
     - name: Install Rust
       uses: dtolnay/rust-toolchain@master
       with:
@@ -52,7 +52,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
     - name: Install Rust
       uses: dtolnay/rust-toolchain@master
       with:
@@ -65,7 +65,7 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
       - uses: taiki-e/install-action@nextest
       - uses: Swatinem/rust-cache@v2
@@ -77,14 +77,14 @@ jobs:
   cargo-deny:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: EmbarkStudios/cargo-deny-action@v2
 
   build:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
     - name: Install Rust
       uses: dtolnay/rust-toolchain@master
       with: