chore(deps): 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/format.yml

@@ -7,7 +7,7 @@ jobs:
     name: Stylua
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - run: date +%W > weekly
 
       - name: Restore cache

.github/workflows/lint.yml

@@ -7,7 +7,7 @@ jobs:
     name: Luacheck
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Setup
         run: |
           sudo apt-get update

.github/workflows/tests.yaml

@@ -22,7 +22,7 @@ jobs:
             install-rg: choco install nodejs-lts curl
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - uses: rhysd/action-setup-vim@v1
         with:

.github/workflows/typecheck.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: stevearc/nvim-typecheck-action@v2
         with:
           level: Warning

.github/workflows/update-copilot-nodejs.yaml

@@ -14,7 +14,7 @@ jobs:
     if: github.repository == 'zbirenbaum/copilot.lua'
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Create directory
         run: |

.github/workflows/vimdocgen.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
     name: Convert Markdown to Vimdoc
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: kdheepak/panvimdoc@main
         with:
           vimdoc: "copilot"