ci: bump the actions group with 2 updates

Bumps the actions group with 2 updates: [actions/checkout](https://github.com/actions/checkout) and [peter-evans/create-pull-request](https://github.com/peter-evans/create-pull-request).


Updates `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](https://github.com/actions/checkout/compare/v5...v6)

Updates `peter-evans/create-pull-request` from 7 to 8
- [Release notes](https://github.com/peter-evans/create-pull-request/releases)
- [Commits](https://github.com/peter-evans/create-pull-request/compare/v7...v8)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
- dependency-name: peter-evans/create-pull-request
  dependency-version: '8'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
...

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

.github/workflows/downstream.yml

@@ -15,7 +15,7 @@ jobs:
     env:
       NVIM: "nvim"
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: tree-sitter/setup-action/cli@v2
 
       - name: Install and prepare Neovim
@@ -31,7 +31,7 @@ jobs:
         run: curl -fL https://github.com/ribru17/ts_query_ls/releases/latest/download/ts_query_ls-x86_64-unknown-linux-gnu.tar.gz | tar -xz
 
       - name: Clone textobjects
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: nvim-treesitter/nvim-treesitter-textobjects
           ref: main
@@ -44,7 +44,7 @@ jobs:
 
       - name: Clone context
         if: always()
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: nvim-treesitter/nvim-treesitter-context
           ref: master