Bump actions/checkout to v6

GitHub actions was complaining that v4 still run on Node.js 20.

Author: gregoire-mullvad

.github/workflows/cargo-shear.yml

@@ -14,7 +14,7 @@ jobs:
   cargo-shear:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install cargo-shear
         uses: taiki-e/install-action@cargo-shear

.github/workflows/ci.yml

@@ -33,7 +33,7 @@ jobs:
             os: windows-latest
             rust: stable-x86_64-pc-windows-gnu
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - uses: dtolnay/rust-toolchain@master
       with:
         toolchain: ${{ matrix.rust }}
@@ -43,7 +43,7 @@ jobs:
     name: Check Format and Clippy
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - uses: dtolnay/rust-toolchain@stable
       with:
         components: clippy
@@ -54,7 +54,7 @@ jobs:
     name: Check Documentation
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - uses: dtolnay/rust-toolchain@stable
     - name: Run rustdoc
       env:
@@ -65,7 +65,7 @@ jobs:
     name: Minimal versions
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@nightly
       - uses: dtolnay/rust-toolchain@stable
       - run: cargo +nightly update --verbose -Z minimal-versions