ci: bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...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] <[email protected]>

Author: dependabot[bot]

.github/workflows/check-merge-conflicts.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
 

.github/workflows/mdbook.yml

@@ -31,7 +31,7 @@ jobs:
     env:
       MDBOOK_VERSION: 0.4.36
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Install mdBook
         run: |
           curl --proto '=https' --tlsv1.2 https://sh.rustup.rs -sSf -y | sh

.github/workflows/rust.yml

@@ -21,7 +21,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     timeout-minutes: 60
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Install dependencies (Linux)
         if: runner.os == 'Linux'
         run: sudo apt-get update && sudo apt-get install -y -qq build-essential pkg-config jq dpkg curl wget zstd cmake clang libssl-dev libgtk-3-dev libayatana-appindicator3-dev librsvg2-dev libdbus-1-dev libwebkit2gtk-4.1-dev libjavascriptcoregtk-4.1-dev valac libibus-1.0-dev libglib2.0-dev sqlite3 libxdo-dev protobuf-compiler libfuse2 bash fish zsh shellcheck
@@ -53,7 +53,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     timeout-minutes: 60
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Install dependencies (Linux)
         if: runner.os == 'Linux'
         run: sudo apt-get update && sudo apt-get install -y -qq build-essential pkg-config jq dpkg curl wget zstd cmake clang libssl-dev libgtk-3-dev libayatana-appindicator3-dev librsvg2-dev libdbus-1-dev libwebkit2gtk-4.1-dev libjavascriptcoregtk-4.1-dev valac libibus-1.0-dev libglib2.0-dev sqlite3 libxdo-dev protobuf-compiler libfuse2 bash zsh
@@ -80,7 +80,7 @@ jobs:
   #   runs-on: windows-latest
   #   timeout-minutes: 60
   #   steps:
-  #     - uses: actions/checkout@v4
+  #     - uses: actions/checkout@v6
   #     - uses: dtolnay/[email protected]
   #       id: toolchain
   #       with:
@@ -100,7 +100,7 @@ jobs:
   #   runs-on: windows-latest
   #   timeout-minutes: 60
   #   steps:
-  #     - uses: actions/checkout@v4
+  #     - uses: actions/checkout@v6
   #     - uses: dtolnay/rust-toolchain@nightly
   #       id: toolchain
   #       with:
@@ -121,7 +121,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 30
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@nightly
         with:
           components: rustfmt
@@ -131,5 +131,5 @@ jobs:
     name: Deny
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: EmbarkStudios/cargo-deny-action@v2

.github/workflows/terminal-bench.yaml

@@ -39,7 +39,7 @@ jobs:
         df -h
 
     - name: Checkout repository
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
 
     # Captures git hash of branch to query specific S3 bucket
     - name: Set git hash

.github/workflows/typos.yml

@@ -14,7 +14,7 @@ jobs:
     timeout-minutes: 30
     steps:
       - name: Checkout Actions Repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
       - name: Check spelling
         uses: crate-ci/typos@master
         with: