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] <[email protected]>

Author: dependabot[bot]

.github/workflows/panvimdoc.yaml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     name: pandoc to vimdoc
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: readme
         uses: kdheepak/panvimdoc@main
         with:

.github/workflows/tests.yaml

@@ -11,7 +11,7 @@ jobs:
   stylua:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: JohnnyMorganz/stylua-action@v4
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
@@ -21,7 +21,7 @@ jobs:
   luacheck:
     runs-on: ubuntu-22.04
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Prepare
         run: |
           sudo apt-get update
@@ -33,7 +33,7 @@ jobs:
   selene:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install selene
         run: cargo install selene
       - name: Run selene
@@ -42,7 +42,7 @@ jobs:
   typecheck:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: stevearc/nvim-typecheck-action@v2
         with:
           path: lua/
@@ -57,7 +57,7 @@ jobs:
         neovim_branch: ["v0.10.4", "stable", "nightly"]
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Install Neovim
         uses: rhysd/action-setup-vim@v1