Bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/docs.yml

@@ -19,7 +19,7 @@ jobs:
     name: Build documentation
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Setup Pages
         uses: actions/configure-pages@v5
       - name: Install Deps

.github/workflows/release.yml

@@ -25,7 +25,7 @@ jobs:
     env:
       TM_DATA_DIR: /usr/share/task-maker-rust
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install Deps
         run: |
           apt update
@@ -78,7 +78,7 @@ jobs:
     name: AUR
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Build PKGBUILD
         working-directory: tools/aur/task-maker-rust
         run: ./gen.sh > ../../../PKGBUILD

.github/workflows/rust.yml

@@ -10,7 +10,7 @@ jobs:
         os: [ubuntu-22.04, macos-latest]
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Install Deps
         if: startsWith(matrix.os, 'ubuntu')
@@ -47,7 +47,7 @@ jobs:
     name: Clippy
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Install Deps
         if: startsWith(matrix.os, 'ubuntu')
@@ -77,7 +77,7 @@ jobs:
     name: Format
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Install Rust
         uses: dtolnay/rust-toolchain@stable